Put quite a few hours into it now and thought I would share some thoughts (playing on PC):
Honestly I'm starting to enjoy it more and more. A big part of that is due to not having the game crash (or a server crash) on me in over a week, so for me stability is much improved. I can now get stuck into actually learning maps, weapons, and vehicles.
There are still issues, hit detection is an ongoing gripe for me. For the last couple nights I've been trying to unlock all the shotguns and I lost count of how many times I went around a corner, shot someone point blank in the chest, and then proceed to get gunned down by the same person who took no damage... Not to say shotguns are broken, I've found them extremely useful in TDM/domination (Saiga 12K + full choke is extremely effective in tight corridors/close range) but the lag compensation (or netcode or whatever the correct term is) is still definitely sub par when compared to the current state of BF3.
As for the current state of game balance, there is some work that needs to be done. Chiefly, the mobile AA. I played a round a couple nights ago on Atai Range HC Conquest and decided to jump in the AA for a bit. I practically locked down the enemy air and thanks to the Zuni rockets, even tanks and LAVs weren't very hard to take down. Really needs a range reduction on the primary cannon since as it stands, it's basically a mobile anti vehicle sniper platform.
The attack boats are also somewhat OP as they seem to be able to soak a lot of damage and with the burst cannon and TV missile, can really dish damage out as well. I think a reduction in armour (or maybe just being easier to disable) and possibly longer reload times for the primary cannon would help balance things out a bit.
MBT seems fine, similar to what I remember the BF3 was like. LAV is also pretty similar from what I can gather. Jeeps are ridiculously fragile now, or at least it seems that way to me. Bikes are a better way to zip around imo.
As for air vehicles, I can't really comment since I can't fly for crap. I think the choppers are more responsive/easier to fly but I'm still pretty horrible. I have found that the little birds seem a bit OP, especially when they have an engineer or two repairing them. Apparently the transport choppers can also be a pain to take down though honestly I haven't run into many issues with them.
For infantry weapons, almost everything appears to have had a recoil or spread reduction when compared to BF3. Assault rifles are still, for the most part, the best weapons in the game. ACE 23 is a popular choice (I prefer the M416 purely based on looks), haven't run with it much but it seems decent. Carbines are good, so good in fact that they makes many other class specific weapons redundant imo. Haven't quite figured out where the SMG's factor in yet, they have very high ROF/good hip fire so obviously good in close quarters but I still find carbines to be preferable in most situations. LMG's are ok, nothing special apart from large ammo capacity and suppression. I have had some pretty good rounds with them though (PKP and Type 88 are both good) and the accuracy of LMG's in general seems to be better than BF3. Sniper rifles are decent, reasonably powerful (one hit kill on hardcore...) and seem to feel better in general compared to BF3.
DMR's are the biggest let down to be honest. Weak, low ROF, and bad recoil. Was trying to unlock them all but gave up, I just couldn't find the right situation for them. If you want something accurate at medium range then an assault rifle with a barrel modifier and potato grip/stubby grip is all you need. Sniper rifles are much more effective at long range, and up close practically everything out guns the DMR. SKS seems somewhat useable thanks to it's ok recoil and higher ROF but still not what I would call very effective.
Bugs wise, I'm still being hit by the no audio bugs on a regular basis. Pretty damn annoying to be honest. Not sure if the latest patch fixed the one hit kill bug (gonna wait for some analysis on that). Still sometimes have issues when trying to join matches (get halfway through loading a level then drop out...). And that's it for the most part (excluding hit detection).
All in all, more enjoyable, but far from perfect.