SP

For people complaining put the difficulty on Hard. Found the SP presented tactical examples of skirmishes - being flanked. AI was solid, but not overly intelligent. Campaign was short, but you also have co-op, and considering the fact the SP is a significant improvement. I would rate this game 75% without multiplayer. Comparing this game to MW2 really isnt fair. However, if you compare it to Black Ops it rightly murders that piece of crap. Some WTF moments and some awww shit need a hole to hide.

MP

The bread and butter of Battlefield 3 (the proper sequel to BF2):

Knifing -toned down and balanced. A good knife is generally from behind (just like in real life)

Stingers -soo, much fun harassing aircraft (I <3 Caspian)

Maps -fairly balanced no matter what you play

Ranking -takes time, but does work. I'm impressed that attachments transfer to weapon variants. Ability to use flying UAVs and upgrade AA is appreciated.

My Experience Online

Load up harbour map. Use SMAWs to knock out tank at C railroad, run to dock and camp water dock taking out infantry and setting mines on enemy vehicles. Mini chopper come in for a strafing run and takes me out.

Two seconds later I'm parachuting from a mini chopper and stinging the enemy heli. Hit the ground and jump into a light tank, then procede to pummel the enemy dingies as they sink sink sink into the abyss. I watch in horror as friendly stingers and tanks pummel the enemy tanker ripping their aircraft to shreds. ***This is WAR*** Thats what I say until two seconds later when my light tank shows me its 'lightness'.

I spawn as an Engineer again. This time I run down the railway track trying to avoid two enemy tanks, I call in air support and sit back pummeling the MBTs with SMAWs. Blow up one and help disable the second. Enemies are clearly spawning at C now. Fall back where I am summarily shot in the back by enemy machine gun fire.

I agree with most of what you said i still feel that there are some issues here and there. Like the upgrade balancing on some things. Take the jet, should flares really be an unlock? I mean if your the new guy and not completely useless flying a jet all you have i the nose gun that takes so many shots to actually kill a vehicle and all the time your trying to avoid lock-ons. It seems that  its a one sided battle most of the time. Its not a great insentive as you have to fend off everyone else from your team to actually get a jet and then you have to get it enough times to actually use it to get enough XP to unlock the flares etc. It can sometimes seem a little backwards to me. 
As for level balancing, Operation Metro (although to be clear I hate this map with a passion so perhaps there's some unintentional bias on my part). If you start as the RU (that's the side with the cafe right?) then its way too easy to be pushed back to your spawn and just be spawn camped for the rest of the map. I mean I get that its all dependent on your team as I have had great teams and terrible teams starting on that side of the map but even then it does still feel a little offset. one of the last times I played that map on conquest the enemy team took the cafe and then just sat in the buildings spawn camping. It would have been nice if my team were not shit or if the other team were not cheap but I feel the flag placement in metro specifically is a bit off.
That aside I am still enjoying BF3, overall it does seem pretty well balanced and none of the classes seems overpowered. Almost all of the maps are great although going ahead with DLC I would like to see some a large map with both close quarters AND open areas instead of either a large open map OR close quarters map.

I agree with everything except knives. They basically don't work unless the person is not moving. It's pretty annoying when a guy runs around the corner, you hit the knife key, see the knife hit him (sometimes even blood), then he proceeds to kill you anyway.  It feels like when they accidentally broke them for a little bit on BC2 before they fixed them.

I agree with pretty much all of this. I love the way the knives work in this game.