Been playing the Singleplayer and the multiplayer for a bit now, and here is what I got to say about it. First off the game plays just like mw2/cod4 with improvements here and there. I like this because since im so familar with those games I picked up the controls pretty quickly and started owning.
For the Campign, I played through about half of it currently and I think its pretty awesome. Even though they're using the same engine I think the game looks great! The singleplayer story is pretty linear (what do you expect?) but its still a joy to play in my opinion. As for the Multiplayer, I agree it does feel like mw2/cod4 with new guns, maps, and killstreaks, but I think they did a good job of making it fun and its very easy to get hooked on. One thing I like personaly about the multiplayer is the level of custumization with the guns. As you play with each gun you can unlock more features for it, and not just attachments and camos, thinks like reciol, weight, and much more. I think this is a very cool addition to the game franchise. Also the game has dedicated servers that seem to be fully custumizable minus the # of players that can join, which seems to be limited at 18. One last thing I'd like to add is that I had no problems getting this game up and running, this doesn't really factor into my review but that gets a plus in my book. All in all think MW3 was a pretty decent game. The people who are complaining about the graphics have to remeber that Sledgehammer didn't have as much time to work on that aspect of the game, but I think they made it a a pretty soild game. I personally like the graphics of Mw3, they are just right for my computer. I couldn't find any major problems with this game yet so I would give it a 4.5 out of 5 stars.
P.S. We should get a server !!!!