Got a beta key from EB Games yesterday when I went to trade in some old PS2 games and buy GoW III and GTA IV. Only played for about half hour so far. To sum it up it's kind of like BC2 but not as good and with killstreaks. The guns seem to take almost a whole magazine to kill someone. Pretty typical unlock system whereby as you play with a class you unlock things like extended mags, scopes and new weapons. I've only played TDM, gonna try to objective based game later and see how it is.
EDIT
Had some more play time last night and yeah I gotta agree with Cale, the objective based mode is so much more fun than TDM. Sure it's your basic attack/defend game mode but the terrain layout is good and the way it changes as you get closer to the enemy stronghold makes it interesting too. I've mainly been using the infantry class. So far I've unlocked the extra mag, red dot sight and the PKM/M249 LMGs.
I like the way the "killstreak" rewards work. They're called scorechain rewards. Basically everything that you do that earns you points such as normal kills, headshots, kill assists, planting bombs, securing areas, revenge kills etc all go towards your scorechain. At a certain amount of points you get scorechain rewards such as UAVs, mortar strikes and air strikes. It's a great concept that works very well so you can still earn streak rewards without having to camp in a room with a claymore by the door like some other fps games.
All in all it is a pretty solid FPS but right now I'm not sure that it brings anything new to the genre. For me the overall quality of the single player mode would determine if I was to buy it or not.