The chaps over at BF3Blog.com have posted Battlefield 3 Alpha impressions. Here's an execerpt:

Gameplay
 Feels more like Battlefield 2 than Bad Company 2. The pace is a bit quicker than in BF2, but it appears it's because of the map and the Rush mode.
 You can now strafe run, which adds a lot more than it sounds.
 You can see your legs/feet when looking down or jumping over things. It's not as weird as it sounds.
 No bunny hopping or dolphin diving.
 3D spotting has been revised. It feels like you need to be more accurate when spotting enemies than in Bad Company 2.
 Classes are a lot better and make more sense (Assault with med kit, Support gives out ammo).
 Everything ran very smooth at high frame rates, it gave it a bit of a "Call of Duty" feeling at times.
 The game appears to be ready for in-game advertising support (banners etc.). Although it could be just random BF3 banners posted.

Guns
 Hit detection feels much better than in Bad Company 2.
 Guns look, sound and feel differently from Bad Company 2. It's more like BF2 than BC2.
 Muzzle flash on guns has been reduced compared to BC2, now is on par with BF2.

Audio
 Just as crisp and lifelike as in other Battlefield games. It sounds more realistic in BF3, kinda like "war tapes" in Bad Company 2.
 There's still automated chatter from soldiers around you, including enemies (which reveals their position, like in BC2).
 No commo rose :(

Vehicles
 There was only one vehicle, the LAV-25 APC. Controls felt like Bad Company 2, but the cannon firing and sounds were much more realistic, as if you're in a real APC.
 It felt like it took a few more rockets to completely destroy the LAV compared to Bad Company 2.

Graphics/destruction
 The game looks great, no way around that.
 Animations are way ahead of Bad Company 2 or any other FPS.
 Destruction feels more limited than in BC2. There are buildings you can destroy, buildings you can't. There are walls you can destroy, and walls you can't. There's no real way of telling which is which.
 There is also a lot of cover that would have been destroyable in Bad Company 2, but isn't in BF3. (UPDATE: according to some, destruction has been limited in the alpha for testing purposes, which would explain what we experienced).
 The lighting is amazing, both in doors and outdoors. Also, you can only shoot out some of the interior lights, not all.

Misc
 Award pins have been replaced by BF2-style ribbons.
 There are a bunch of new guns, like the G36C, MP7, M27.
 There are now faction specific weapons and rocket launchers.
 When M-Com stations are armed, a C4 device appears on it. When disarmed, the C4 disappears.
 100 points are given for a kill, +10 points for headshots, +30 for kill assist etc. You get 200 points for arming M-Com, another 200 for destroying it.

Overall:
 The game feels a lot more like Battlefield 2 than Bad Company 2, contrary to what many people think. It was hard to comment on pace, since it's Rush, limited to 32 players, with tight combat areas — so pacing will naturally be fast. On open, conquest maps with 64 players, I can imagine it feels a lot more like BF2. Also, note that these impressions are for an alpha version - it's far from a finished product.

Source: GGMania headlinesGGMania.com - Daily Gaming and Tech news