General Gameplay/Interface

Let me start off by saying that the build we played at the GeForce LAN was light years ahead of the Beta. It's the theme that will probably run through the rest of this post; it was a great relief to see how much work DICE has put into polishing BF3 up for the final release. Off the top of my head, asides from few bugs (noted at the end), I didn't run into any of the glitches people were having in the Beta(such as rubbernecking or map glitches.)
Chat interface. FIXED. The chat text now blends in and matches the rest of the GUI. It is in the same location but that black background is no longer there; the chat is overlayed on the screen just like in previous Battlefield games.
Squad screen. FIXED. Pictures of the new squad screen have obviously already popped up on Reddit, and I can't really add anything asides from confirming that it looks exactly as it does in the pictures. However, there still isn't a "Join Squad" option that lets you populate an empty squad. You click "find Squad" and it automatically puts you in a squad just like Beta, although based off the new design it seems like they will have full squad join functionality in the final build (Crash7800, can you back a brother up?).
3D spotting was quite a bit more refined in this build than it was in the Beta. If you spotted someone and then they got behind cover(buildings or vegitation/rocks), their on-screen 3D spot dissappears immediately. No more firing at doritos in the foliage.
Minimap. FIXED! The minimap has been vastly improved and is almost on par with the map found in BF2. It's a nice, full minimap now: you can see all the flags, your teammates, empty vehicles...etc. The only thing that seemed like a minor issue is that the zoom levels seemed funky on some maps (like Operation Firestorm) and there wasn't an option to set whether the map would rotate with the player or remain locked onto the compass.
Rocks can no longer be shot through. (LULZ)
The Options menu is now accessible while dead or alive.
The kill cam screen seems to have been shortened in duration, although this could have just been on TDM.
There are customizable camo options available for the picking now. From what I could see there were a few solid color uniforms (Black, Blue, Green, Tan, Grey), a few different types of camoflouge (desert/forest/urban), and a few special ones like the SPECACT uniforms and one named the "Dr. Pepper" camo which I can only assume will be tied into a marketing blitz just like the SPECACT stuff was tied in with them during BC2. Each camo "selection" had a corresponding Russian and US version so that you would never be able to put on the same uniform as the opposing team.
Hit detection seemed vastly improved. Granted, we were in a LAN environment, but I believe the BF3 servers were actually being hosted down in LA (7 hours away). TDM and 32-player Rush were silky smooth but there was still some weird lag on the 64-player conquest maps. It was fairly rare though, so maybe it was just actual internet traffic issues.
There was a notification now for you to press "Q" if you needed ammo/medic that appeared to pop up automatically if you needed either of those things.
The new in-game icons that show up over teammates, dead players, and dead players who need a revive have been completely overhauled. They are thicker and a bit brighter; the end effect is that they are much more noticeable.
They bumped up the points you receive for completing team objectives. Off the top of my head, neutralizing a flag nets you 200 points, and capping it gives you an additional 250 points. MCOM attacking/defending saw a similar boost.


Weapons

The damage model for the weapons, on the whole, feels much more polished than the Beta. The damage glitch where people would take more damage due to sprinting is noticably gone and the gun play now feels much more balanced and even.
Firing an unsuppressed weapon marks you on the enemy's minimap for a few seconds; there is now a tangible benefit to rocking the silencer. Most of the teams in the 4v4 TDM tourney had silencers on everything because of this fact.
The SUNFIRE TACTICAL LIGHT OF THE GODS has been toned down just a bit. I'd say the circle of light is maybe 20-30% smaller? I didn't run into too many people using it.
UMP45: Definitely toned down. I didn't play with it much but there weren't lots of people running around with it, even on some of the tight CQB maps that were played in TDM. It looks like it still packs a punch at close range but loses power quickly at range.
M39 EMR: Pretty sexy, didn't play with it a lot but it seemed like a slightly better version of the SKS.
SKS/MK11: Seemed like they were toned down from their god-like powers in the Beta, although it's very possible this is as a result of the fixes to the damage model that DICE made. (See above)
Bolt Action Snipers: Seems like the bolt action animation has been tweaked to make it harder to quickscope like you could in BC2 and the Beta.
T-UGS (Recon Emitter): Now works as advertised with people popping up on your mini-map who are moving within the range of the emitter.
SOFLAM: Didn't try it. Sorry :'(
Javelin: Worked like a ground version of the stinger missile, it didn't pack much of a punch against heavy armor. Only played with it a few times. Locks on, fire and forget.
Mortars: \o\ \o/ /o/. These things are a complete blast. You place them on the ground just like a T-UGS or the Mobile Spawn Point. Once placed, your minimap expands and a ret appears on the minimap that you can drag around for a set range. Click, fire, wash, rinse, repeat. At first they seemed like they would be OP but they have a lag time and a margin of error that prevented utter domination. I can see some really interesting tactics being developed for this in competition. It's perfect for bombarding a squad that is camping a certain area. More info down here.
M16A4: This 3-round burst varient of the classic workhorse was a ton of fun to play with. Combined with the "Heavy Barrel" attachment it seemed to be really solid at long range.
KH2002: This was the other assault rifle that wasn't in the Beta. It had a nice burst mode and seemed suited for medium-range engagements.
T88: Didn't play but one round with it: didn't even fire it. No info. Sorry :'(
M1911: Pretty sexy. Packs a punch. Has the most varients of all the pistols (Regular, Suppressed, Tac Light, Suppressed AND Tac Light). Good times.
M44 Scoped: Sniped a few dudes on Firestorm with this, seems like a great weapon to finish people off at medium range. However, the firing speed was slow.
SG552: Decent engineer weapon. Didn't play with it much. No info. Sorry :'(


Maps

Damavand Peak. (TDM). They only had this map playing during the TDM 4v4 tournament (unless I missed something?). It took place in a fun quarry area that had lots of industrial machinery and massive dump trucks (TONKA TRUCKS!) all over. Tight infantry action. I tried to peek around to see the rest of the map beyond where the TDM area was and it looks really big. Awesome vibe.
Grand Bazaar. (TDM). Again, I only played this one in the 4v4 tournament on TDM. There was a mosque, a market area, and then some streets and backalleys that were intertwined to make a really layered TDM map. It was obvious that DICE really put time in to give each of these maps character; Grand Bazaar had a unique sense of place. Can't wait to see 32p Conquest on it.
Operation Firestorm. (TDM, 64p Conquest, 32p Rush). First things first: this map is huge. Hell, each side starts off with something like SIX heavy armor vehicles on each side at their main spawns. Rush was just the 64p conquest map, but you fought from the US spawn across four stages to the RU spawn. TDM took place at one of the flags and involved three warehouses and a crate yard that had a lot of awesome terrain for tight TDM combat.
Caspian Border. (64p Conquest). Not much to say here. The fences were fixed so that jeeps no longer get stuck on them. I didn't manage to take down the massive antenna, although you are now able to take down the radio tower that sits at the "Hilltop" spawn; it falls over on to the rocky area behind the flag.
Operation Metro (TDM, 32p Rush). There were a few minor changes to the map in regards to shrubbery placement. Asides from that, it seemed just like it did in the Beta. TDM takes place all through the last stage of Rush: the "Apartments" area. It looked like fun, but they were having issues with it on TDM so they took it out of the tournament rotation.



Bugs/Complaints

The only two recurring bugs I noticed both involved the ret. The first one happened quite often when I switched back to my main assault rifle after being scoped in on the M320 grenade launcher. I would get the grenade launcher ret from BF2 overlayed on top of the normal ret from the rifle.
The second reticle bug was one that I noticed happening a few times in the Beta. I would unsight from my iron sights only to not have my normal white reticle pop back up. Switching to pistol and then back again usually fixed it. Hopefully this gets fixed.
The only design complaint I had with the new build is that for some reason they've change the medic pack icon on the minimap and in-game to this funky-looking band aid instead of the standard "Red Cross" in BF2 and BC2. It looks really dumb and isn't intuitive in the least bit.



TL;DR, DICE fixed most bugs and issues, game is super polished, the Beta woes are no more. The (almost) final build is looky QUITE SEXY. 10/25 can't come soon enough.