For ones that I really didn't make it through, I found Killer 7 intersting and ambitious, but so very unfun in its execution.
Little Big Planet, while very charming, kind of puts me off with its somewhat dodgy controls, but I really love its charm and atmosphere. That and I REALLY don't like platformers.
Killzone 2, yes the graphics were fantastic, yes the gameplay was excellent, yes the atmosphere was great, yes the boss fights were fun. It's just... god... Rico... Garza... Natco... if you all just shut the hell up I would REALLY enjoy this game but NOOOOOO you have to spout your annoying dialogue ALL THE TIME! Even Call of Duty 3's aweful, aweful story was better than this.
Fallout 3 (kinda), I really enjoyed the first play through, well, except the ending. But knowing how shallow the overall storytelling is and how unrewarding the sidequest plots are (ex. The Dunwich Building) I just haven't been able to bring myself to replay it. Also the enemy variety is really small, something I didn't notice the first time, I got really bored of fighting the same Super Mutants, Rad Scorpions and Bears over and over again and killing them in exactly the same way every time. But of course I respect it, it's deep and open ended and very, very pretty.
Grand Theft Auto 4, technically impressive, interestingly plotted, great characters, good gunfighting system but in the end it's the shit tastic Car Controls that really ensured that I would never really enjoy playing this game. They made driving an almost unbearable chore and they really suck for that. I'll stick with Saints Row 2, where driving is fun. Also, Brucie, I really, really hate Brucie.