I've tried it out with a few different builds, and it just really seems kind of useless. I mean sure, its a one hit kill and it is oh so satisfying to get a kill with it but I just don't see any real viability in actual gameplay.
 
So let's just lay out the differences between the knife and other equips:
- Guaranteed one hit kill
-Can be picked up and used again
-Can be "cooked" for an infinite amount of time with cross hair
-Is faster in deployment than any other equipment 
-Possibility of it ricocheting off a wall and killing
-Kills are mostly silent
 
Now really, when it comes down to it I think the Semtex does a better job than the Throwing Knife at what is generally the same job. The only reason I say the Semtex is not a guaranteed one hit kill is that it is possible to actually survive being stuck if it is stuck on your Riot Shield and you have a Blast Shield equipped.
 
The other two factors, recycling and quickness, I think are both also somewhat shaky. In my experience, if you actually go one on one with someone bullets will usually kill more often than the knife. This is due to two factors. One being that gun can instantly be fired from the hip and the fact that the damn thing is just hard to hit with. I suppose that if you took the time to actually get good with it then it could become a potential ace in the hole to fall back on, but in reality I think either grenade wins out here because of their ability to get numerous kills without repeated use.
 
Not can grenades get multiple kills, but they can also be thrown in areas your character can't see. I'm sure everyone here has either gotten a kill or at least been killed by a grenade thrown over a wall or onto a point of interest. The knife seems especially useless in this situation as it has to be picked up to get another kill, and that crucial few seconds could mean life or death. Now a perk like Scavenger could certainly fix that problem, but in that case why wouldn't you just use grenades anyway?
 
 I suppose you could say that the option of silent kills may come in handy in game types like Search & Destroy, but even then one could argue that a silenced weapon or just simply a regular knife attack is a better choice.

The only reasonable argument I've seen for the knife is when combined with the Riot Shield. The Riot Shield player has no means of attack besides melee without exposing themselves, and when you are using a Riot Shield that is the last thing you want to do. Especially if you are being shot at. The two big factors that really come into play with this set up are the quick deployment time and recycling, though one could argue that quickness is really the only determining factor. Once again however, it takes a lot of practice to get good with this combination. Even more so than just using the knife regularly, because unlike any other primary weapon in the game the Riot Shield has no targeting reticule at all. While I'd rather not start a Riot Shield debate here, I would also like to at least state that I think the Riot Shield is a very specialized Primary that is only truly effective in certain situation. While there are plenty of great Riot Shield players, I just think that the Riot Shield is rarely going to be a determining factor in the hands of the average player and only in certain game types.
 
So, long story short the Throwing Knife friggin' sucks.
 
Discuss.

Yeah i was so excited when i unlocked it, then realised it wasnt really worth loosing your semtex over. Never used it since. 

I use it. It's my fav, especially with Scavenger you don't have to worry about picking it back up.

The throwing knife really only seemed viable when in close quarters, but at that point you might as well just melee everyone. Faster and has a larger range. Biggest disappointment for me was that throwing knife.

The satisfaction of the kills make it sweet, but yeah, not really the most tactical option. I kind of suck with semtex though so usually have a knife onhand just for the heck of it.

I have gotten some kills with it that I wouldn't have elsewise...but no its not worth it for the most part.

I love the throwing knife. For some reason, I absolutely suck with grenades. I can definitely see why people don't perceive it as a viable option, but it's not the worst choice for equipment in my opinion.

Its not really a viable equipment; just like how C4's weren't very viable or used in COD4. They're fun to use (like how people would throw down a C4 on the floor and blow it up on everyone they see).
 
For me though I use it to conserve ammo and use it as an alternative to meleeing. I don't know, it just gives me more of a satisfaction; even if I was standing right behind the guy.

The knife seems to drop too quickly. It needs to be thrown with more velocity.

I used to keep the throwing knife on one or two classes just for fun, but tonight I replaced it with Semtex. While they're satisfying to kill people with, they get me killed far more often than they get me kills, and I find Semtex far more useful in just about every situation. If you can actually reliably get kills with the throwing knife, I envy you, but I suck with it. Semtex 4 lyfe yo.

I'm pretty bad with semtex and grenades I've only managed a few kills with them. 
Throwing knifes in the other hand, I have quite a bit of.  
I've completed the throwing knife challenge 2 weeks ago. Which I believe is 30 kills?  

I use it more as an insult, not to win a round.

For fun, and mocking your enemies it is.

Throwing Knife + Riot Shield = Win

Besides General Shepard, my Throwing Knife kill count is zero :(

I've only had one kill with it, and that was when the game was still pretty new, I stumbled onto 4 guys from the other team at once and freaked out and pressed both the fire and grenade button at once, Managed to shoot 2 of them and kill one more with the knife before being taken down, was pretty epic but also total fluke

I use it and get tons of kills with it, it was better when I used a heartbeat sensor though..
 
The trick is when you see there is someone around a corner with your heartbeat sensor, you ready your throwing knife and as they come around the corner you throw it at them, works a charm.

If you insist on using a Riot Shield the knife is a much better option compared to semtex. Semtex takes a good 2 seconds  to pull out not including the time it takes to throw it. Throwing knife is nearly instant. So you corner someone, they lay into your shield, and when they reload you just flick a knife in their eye. Take flash or stun for added ease of use of the throwing knife and you've got a grade A asshole build. :Thumbsup:

I'm a player that likes to go out of his way to flank and hunt the enemy, which makes the throwing knife absolutely awesome. I've gotten some kills that I wouldn't have gotten otherwise, such as clothes-lining enemies that, otherwise would have likely gunned me down had I gone out of cover.

It's highly situational, and extremely useful if you know when to use it. 
 
Just the other day I popped around a corner and two guys were there, sights up, cruising slowly around the map looking for fast movers like me. If I'd tried to gun battle both of them, I wouldn't have had enough bullets to take them both out. So I quick-killed the first guy with the throwing knife and instantly went to work on the secod guy with my UMP45. Took 'em both out, went to get my knife back, and melee killed the third guy I found hiding out behind them with a sniper rifle. 
 
Learn how to use it properly, and it'll be your best friend at close-mid range.

A grenade can get the opposition to leave their safe position and that creates an opportunity to kill them.  I think it might be include for people who've done everything and now just want to show off.  I have a hard enough time trying to hit people with a gun, I'd find it impossible with the knife.
 
DLC needs to introduce ninja stars and boomerangs...now that would be fun. ;-D

I've noticed that it usually takes a bit too long to leave the hand,  I'll throw it an enemy, get killed, and the knife drops to the ground as if I never threw it.

It takes some practice to aim right, but it can be pretty satisfying and effect when popping around corners and someone is out of knifing range.

I usually use the throwing knife with LMGs, the long reload times seem far less daunting when you know you have a way to instantly kill the guy who will come around that corner when you're half way through that reload.  Switching weapons is just too slow in that situation and the guy coming for you is likely to try to knife you or take the time to try to get a headshot, a quick knife to the chest will save your life 9 times out of 10. 
 
It's also pretty useful if you're chasing a guy and know you won't be able to knife him or shooting him will attract too much attention.   To be honest though, I tend to stick to either the Semtex or Frag, scaring someone out of cover is usually a lot more useful than stopping someone stabbing you. 
 
The real question is why use the C4?  Surely that's just a bit of a camper's weapon.

Two Words: Riot Shield. If you are willing to give up the blast shield you might be surprised how many people don't expect getting a knife in their gut when you charge at them. 
 
But otherwise yes, Throwing Knife kind of sucks.

i use it on my lightweight class. i don't find it useless, you just have to get used to the drop if you're throwing long distances. the only problem with it is that if you're running into a group of enemies only one will die as opposed to a grenade.

The throwing knife was never meant to be tactically useful - it was made for the greatest, most epic kills you have ever seen.
 
The other night I saw a killcam on Wasteland where someone blindly threw one into the opening of the bunker, skipped it off the floor and hit a camper in the balls.

I like the throwing knife if only because it makes for the quietest kills of any weapons. It's great for when you're behind enemy lines using a stealth class, and there's a guy sitting there sniping or otherwise camping, in the open. You can throwing-knife them, and nobody will hear anything but the guy dying - no indicator of where it came from except if they saw the trail, or watch the killcam.

Personally, I find the throwing knife preferable to firing my primary weapon in some cases. I had just been inserted into a free-for-all match only to see someone standing about one hundred yards away from me. Quickly tossed one at him and got First Blood.

Obviously yes, if you know how to aim.

I use the throwing knife for most of my classes and i'm beast with it. i get kills all the time with it. 

"
   I haven't played the game but a friend showed me this.  

  Seems effective. "

I've been using it with my Knife Runner class. It's effective in some mid range situations if you're decent at aiming with it, but I found that I had to put a lot of effort in to even be decent. But when you get that match winning kill through window into the back of the other guy's head and everyone cheers for your shot, it feels pretty damn good.

I think it's too hard to hit people with it for it to be effective. It's more of a thing you use for fun hoping to get moments like shown in that video. I've tried to only use throwing knife for an entire round and get one, tops two kills with it.

Personally I find the throwing knife to be very useful, it definitely has its advantages.. the main fault I have is the Riot shield since I find alot of the time people just shoot through it or knive through it, pretty poorly designed and seems like a last second implement imo. 
 
But the throwing knife is a blast when used correctly, scavanger and lightfoot seems to work well together and personally I use Ninja for Perk 3. ^^

I'd also rather use semtex as my equipment more effective at taking out a player or two.