OK, I'm buying this when it releases for a few reaons:
The demo runs exceptionally well with an MP3 player, emule, and X-fire all running in the background on my system. No stuttering at all, with everything cranked up wide open.
Having been a BF series fan for a while, I can't wait to see what they do with vehicles in this game. I never played COD, however this demo has impressed me quite a bit. The tanks in the demo look outstanding, just wish it'sd let us drive them (maybe a MP demo will come out that does that).
+ from what I understand they are going to release an SDK for this thing, that alone will generate a ton of mods based on it.
About the only thing I don't like is the insane accuracy of the weapons. I was able to consistently snipe with an SMG, pulling off one round head shots. The melee feature rocks, however.
From the demo I'd give it an 7/10.