I've been playing a lot of the Mass Effect 3 multiplayer, and for the most part enjoying it. But it is janky as hell. Part of it is just the nature of the combat--for instance, the game doesn't do a good job of letting you know where you're taking damage from or what exactly is doing damage to you--but there are a slew of issues with the game I'd like to see altered and/or patched out in a forthcoming update. 
 
The bugs I'd posit need addressed most include: 

• The Vanguard bug wherein you bounce uncontrollably above and under the map after charging a freshly-killed opponent.
• The Vanguard issue where the Biotic Charge does not activate right away, or after a single (or multiple) button presses. 
• The Infiltrator bug that, in the situation an Infiltrator is the last man standing, allows the enemies to see him/her even whilst cloaked.
• The bug that prevents teammate revival if an enemy, or multiple enemies, are standing on/near the fallen teammate. 

• I hate being hit by projectiles that clearly pass my character to either side. Geth Rocket Troopers are perhaps most guilty of it, but Ravagers and Banshees get the benefit of the doubt pretty often as well. More or less, if you're out of cover when an enemy fires a high-damage projectile, you will likely take the damage from the projectile regardless if you enter cover and especially if you evade the projectile with a roll. 
• The Phantoms need a noise or a wind-up of some sort to their projectiles. The way it is, you can't really engage the Phantom without sacrificing most of your barrier/shields/health. Given their (admittedly rare) one-hit-kill melee attack, their cloak, and the power of their attacks, they're arguably the second-most devastating enemy after the Banshee. 
• Speaking of Banshees, there probably ought to be a limit to how many are on the battlefield at one time. I played a game tonight on Silver where we had to deal with three at once, and with their penchant for one-shotting players without warning and recharging barriers more quickly than any enemy, they greatly tip the balance of the fight in the enemy's favor. Which is fine to an extent, since they are a boss-class enemy, but boss-class enemies should still have restrictions, rules to follow. 
• Generally speaking, I'd like to see the enemy generation system spawn enemies relative to the type of wave you're on, not the number of the wave. Trying to hack a single terminal for five minutes on Wave 10 when there are two Brutes and three Banshees floating around, becomes a nigh-impossible task on Silver, not to mention the challenge on Gold. And with an infinite string of enemies (until you complete the hack, at least ), the general balance of the match is thrown askew. 
• Bioware to this point has been good implementing new types of packages on the fly and weekly bonuses for players. I'd actually like to see an intermediate difficulty between Bronze and Silver. Bronze is way too simple. Silver is perhaps slightly too hard to play casually. If all we're doing is adjusting sliders to determine difficulty, I can't imagine a new difficulty strata would be too daunting to conjure up. 

BUG: Let's me rearrange the skills on the skill bar(PC).

scorpion and M37 falcon both have an issue where if you fire it too fast it will consume your ammo, make a pop sound but doesn't shoot any projectile. Bioware try to fix it by lowering it's rate of fire hence forcing you to shoot slower. But they apparently forget that Turian soldiers have a skill called "marksmen"

I think the jump in difficulty between Bronze -> Silver -> Gold is a little to steep. I can play Bronze with 2 to 3 mid-level players withough breaking sweat but Silver gets close to impossible depending on the enemy. Same goes for higher level chars and Silver -> Gold.

Id like them to adjust silver and gold and maybe add one more difficulty at the end to even it all out a little.

I've been having heavy latency issues lately, with heavy rubberbanding, making it almost impossible to aim. I'm assuming this is either me being placed in games hosted by players who are geographically distant or just have terrible connections.

Workaround there, much like the Vanguard issue (also big problems for Krogans), is to be the host yourself. But that's obviously not a scalable solution that will work for everyone.

I hear a lot of people having issues with Brutes and Banshees - but I think that's largely because a lot of groups aren't balanced to take down those enemies easily. Bring someone capable of causing biotic explosions and you'll be laughing. I understand that Salarian Infiltrators can be devastating as well - but I've not managed quite the sort of power I've gotten out of an Asari Adept from a Salarian Infiltrator quite yet.

If anything - I think that some class/race combos may need buffing to be put more in line with Asari Adept/Salarian Infiltrator. I don't think nerfing those classes is the right solution - as it'll just make higher difficulties even more difficult. Also, I think it's rather counter-intuitive how hard it is to find good weapon/race/class combinations at the moment.

As an Asari Adept, you can take out Banshees pretty quickly, and multiple people working together to cause Biotic Explosions can kill them in seconds, regardless of difficulty.

A downside with buffing everyone would be that I think there's a pretty good balance to Silver and Gold at the moment - while I think Silver games are pretty easy (only reason I do bronze at all anymore is to level up my promoted characters a bit, or goof around with a combination I'm not sure about.) and Gold is pretty difficult to the point where you'll probably struggle if you aren't prepared.