Quick review:
+ The game looks fucking gorgeous, especially in the dark. (yes, i've played Killzone 2, move along). The game sounds more like BFBC2 than MW2, a lot more oomph and shit going on. Surprisingly, the music is great and fits into the atmosphere they build. I even liked the voice-acting (Sam Worthington overplayed it a bit though).
+ Some really great set-pieces, more so than MW2 even. There are so many moments that I want to replay again, especially some of the vehicular sequences. They basically tried to just up the ante and go crazy with those badass moments and they pull it off. I have no idea how the next CoD will keep it fresh after all the shit you do in this.
+ Game is a lot longer than I was expecting. Just when I thought it was coming to a close, there was an extra 3 hours in there. Overall, the singleplayer on Hardened took me 8 hours.
- This game is going to be a bitch on veteran. Here's why: There are the occasional monster closet moments where enemies will respawn endlessly until you do something. The checkpoints in single-player are bad, like Uncharted 1 bad. Why they put a checkpoint before a character decides to talk for 5 minutes I have no idea. There are sections of this game where you are not doing anything for 5-10 minutes, that will be annoying to repeat. Finally, there are a ton of 'enemies jump out of nowhere and pre-shoot you around the corner' moments. Tl;dr "this was all in MW2" excuse, whatever. This game will be a pain on Veteran because of these aforementioned things.
- You will see the twist in the narrative coming a mile away. It doesn't really do anything new with story but it is engaging enough and certainly not as fucking ridiculous as MW2's.
- Nuketown. This map is an abortion; why the fuck is it in the final retail product? It exemplifies everything that is broken with the spawn system. (seriously it is horrendous and miles worse than MW2's). Even more egregious might be the fact that you can vote for the same map over and over again, therefore the other players/dickheads decided it would be fun to play Nuketown four times in a row.... UGH. Unrelated aside: Having to buy attachments for each seperate gun is a pain in the ass.
I'd give the game a 9/10. The singleplayer was really awesome (miles better than any CoD's since MW1) and the multiplayer is the same great shit it's been for a while now. Assuming there is a big patch on the way to fix the hacking and terrible spawn system, there is no reason not to pick this up.