It is. It does kinda suck starting out, but that's true for any game with a leveling system - it only sucks because you don't have the neat toys that help you do your job better. There's two modes: Seize Ground, which is a territories/control point style of gameplay, and Annihilation, which is basically good ole' Slayer. Teams are automatically sorted into either Space Marines or Chaos Marines, you don't really get a say in it - however, if you invited buddies to join you before you picked one of the game modes, the game will actually attempt to keep you on the same team as your friends, which is much appreciated.
There's numerous weapons and perks. Tactical Marines have the largest amount of weapons to choose from, whereas Devastators/Havocs and Assault Marines/Raptors have less. Every weapon has its own pros and cons. Perks are unlocked as you level up, or as you fill certain requirements (kill 50 enemies with a power axe/chain axe, for example). Co-op multiplayer is coming out in October, and any experience earned there will apply towards multiplayer as well.
EDIT: Checked some other sites, now that more reviews have gone out. Lowest review I've seen it get so far is an 80, highest being a 90. The classes in multiplayer are fairly well-balanced (for the most part), but there are issues with it - an Assault Marine/Raptor that knows what they're doing can absolutely obliterate almost any other class, save for another Assault Marine/Raptor. Tactical Marines feel a bit weak at times, but have uses. Last but not least, the plasma cannon for the Devastator/Havoc is ridiculously powerful - luckily, you can only get it at level 20.