Sprint. There seems to be unlimited stamina. You can strafe(slightly) while sprinting, which is pretty nice.
Weapon lights. Can be turned on/off via a hotkey(L). Blinds people at close range. Other player's lights are seen as a glowing dot at long range.
Vaulting. When approaching an obstacle you can press space to climb/jump over it. This seemed to work on everything I tried it on. You can not fire while the animation plays(around 1 second). Jumping is still ingame if for some reason the vaulting isn't working on something.
Deviation. Deviation feels pretty good for a vanilla game. As always it's stance-dependant. When hipfiring it's accurate enough to take out people close to you, but that's it. When aiming down the sights you can kill people are range quite effectively. Snipers/marksmen are most accurate, assault rifles in the middle and undeployed machine guns last, however deployed machine guns felt more accurate than assault rifles. When jumping you get maximum deviation, and it takes a second or two to settle again. When going prone you get this animation thing that moves your view around a bit, but the crosshair stays tight. I tried it against a wall, and since the animation is not random it's easy to compensate and fire at the intended spot while going prone. So prone diving works pretty much. However it may just be that they haven't added the deviation increase yet.
Deploying weapons. Machine guns can be deployed on most surfaces like walls, windows and different kinds of cover, as well as when being prone. When prone or standing/crouching next to a deployable surface you just right click once and he folds out the bipod. That locks your weapon to the surface and you can swiwel around the bipod itself(which looks nice) in a limited arc(100ish degrees maybe, could be dependant on the surrounding objects). You can fire via the crosshair or scope in for added accuracy. To un-deploy you just move away from the position.
Rockets. The two rocket weapons on this map were both unguided, and seemed to be fairly accurate with not much drop. Explosion radius was enough to kill guys at maybe 1-2m but nothing extreme(BC2 CG, I'm looking at you).
Squadleader. There were 1 SL per 4 man squad. There was no squad selection/creation menu(yet?) so it was random. The SL was the only player in the squad you could spawn on.
Commo-rose. No commo-rose or communication tool to be seen anywhere. Probably not implemented yet. At the closed presentation we were on before the play test the devs there got asked if BF3 would have a commo-rose a la BF2 or a context sensitive key a la BC2(which means one key, and depending on what you're looking at/doing it gives a different message). He said the commo-rose is awesome, but was prone to causing spam in BF2. He couldn't give a full answer due to the marketing plan they have(gameplay details/news to come at GamesCon btw), but I interpreted the rest of his somewhat dodgy reply as that they were aiming for something in between the commo-rose and the BC2 system.
Spawning. You could spawn on either the team's main spawn or your SL. When having the SL selected your camera spectates him until you spawn. I spawn killed a few guys and spawned too close to the action a few times myself when using the team spawn, so we'll see if they improve this somewhat.
Melee. Melee is BC2 style, i.e. a melee key and no knife in the inventory. I never got to melee anyone(sadface) but my friend got one and said it triggered some animation where he grabbed the enemy and slit his throat in a cinematic fashion. Unknown if it's always like that or only in some situations. I personally hate being helpless because I have to spend several seconds caught in a knifing animation with no way to abort.
Damage. Rifles seemed to kill in around 4-5 shots. LMGs felt the same. Snipers(or marksmen really) in 2-3 shots. This is all non-headshot. So somewhere in between vanilla BC2 and BC2 hardcore.
Hit Detection. The hit detection felt solid and I didn't notice any shenanigans, but it was a local LAN game after all.
Sounds. The sounds were very nice. Really. A bit less cinematic than BC2(which is good imho), and more sharp, snappy or crisp than many other games. And as always there were echo and other sound simulation effects that changed depending on the location.
Medicing. Press 3 to throw a medic box on the ground, which in turn heals people in a radius around it. Press 4 to pull out the defibrillators, then use them on a dead guy to revive. When being revived you start prone, and you're blurry and unarmed for a second or two. It would also appear that you don't auto-heal to full health, more like 80-90% or something.
Vehicles. There were only one vehicle on the map, and I didn't get to use it. It went down real quick seeing as half the team was playing as engineer because of the ironsight weapon the class got. However my friend managed to get in a LAV-25 that was stuck(lulz), and he reports that driver/gunner is shared and that thermal can be activated via right click.
Fire selector. You could switch between single fire, burst or automatic depending on the weapon by pressing V. Not much to say really, it works and can be nice to have although I prefer running on auto and doing manual single fire.
Destruction. The destruction felt a bit toned down from BC2. You blow parts off of walls and stuff, but it took some shooting. When I fired an RPG at a guy in a window, it left a hole approximately 2x2 meters in the wall. I never got to see a building collapse. Overall you could notice that the destruction was there, but it didn't feel like it was the main focus of the game, like in BC2. Less gimmick and more gameplay.
HUD. The HUD can be seen in videos and stuff like that, so I won't go into detail. But generally it felt pretty unobtrusive and it showed the important stuff. The minimap was decent, but not perfect - I'd prefer a more map-like one over the stylish one. And there was no way to bring up a big map. However they keep insisting, like so many other new games, to block my view with these damn score popups.
Suppression. There is some form of suppression implemented in the game, but my vision didn't get impaired every time I got shot at - more like just a few times. Likewise, I only got points for suppressing(yes, you do get that..) after killing a guy a few times despite me killing a lot of guys. I'm not sure what's going on here, but if you can't suppress people every time by shooting at them I fail to see the point. Gimmick or bug?
Mods. They got asked about mod tools at the presentation, and like we already know there are currently no plans for them. They will look into it post-release
Reloading. This is a nice one. If you still have a round in the chamber and press reload, you do a quick reload and just put in a new mag, while if you're completely empty the animation is longer because you need to chamber a new round. Because of this 31 rounds of ammo in total is possible(30+1). Strange thing is that you spawn with that as well - I'd like to see 29+1 as default.
Animations. Animations looked really nice. Reloads were fairly accurate and the running/climbing stuff looked motion capped or at least equally realistic.
E-Sport. They were very secretive, but they hinted at them doing more for E-Sport with BF3 than with previous titles.
Servers. There will be dedicated servers. No word on if it's only through GSPs, but unfortunately I find that likely.
Scopes. The scopes were in 3D and looked nice, but they zoomed the whole screen and not just the area in the sight :/
Prone. It's prone. You're crawling on the ground. Bit nicer movement animations than previous games though.
Ammo. The support class can throw an ammo box on the ground by pressing 3(or 4) which then re-supplies everyone in range. Disappears after a while and the player gets a new one.
Graphics. It looked kinda like in the trailers, albeit a bit smudgy or something that I can't quite put my finger on. It's quite possible that they had it turned down slightly for gameplay purposes, since a pre-alpha game isn't fully optimized yet.
So what did I think of the game? Well you probably noted that I mentioned Bad Company 2 as a reference several times. That's simply because they are very similar. In a good way though, because this feels like an improved BC2 in pretty much all aspects. If you liked BC2, you'll probably need new pants after playing BF3 - and if you despised BC2, you'll probably be sorely disappoint. The gameplay is fast, action packed and at times a bit spammy. However because it did feel more like Bad Company than Battlefield 1942/Vietnam/2/2142, I couldn't help but feel a bit disappointed. But maybe that's just me being nostalgic, and not willing to accept that newer games just wont feel like the older ones?
So will Battlefield 3 be the shizzle? Well I can't answer that question. Why? Simply because the BF3 I'm waiting for is a game with 64 players, a combination of air, ground and infantry working together on big(ish) conquest maps. This demo version had only one of those things - infantry. So guessing what the other components are like is as hard for me as it is for you. What I can say though is that for a vanilla BF game, the infantry part felt very nice, and the 40 minutes I spent in the BF3 area flew by and my heart was pumping for a good while after getting back to my regular seat. So considering this, and if the other parts are equally fun, this game could turn out really good in the end.