PDZ- Single player was a bit of a dissapointment, still, a great game online though.
Condemned- My second favorite survival horror game |Resident Evil 4 is #1

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Madden 06- Graphics are sweet but the game has some minor glitches that set it back a little (Only for real football fanatics)
Call of Duty 2- By far the best 360 launch title. Amazing visuals, A+ single player campaign and good online play when not laggy.
Amped 3- In my opinion this game was phenominal. Graphics were great, story was hilarious, and gameplay was good and simplistic. Only problems were no online and the story mode was a little short.
PGR 3- I loved this game. The enviroments are wonderful and the online is some of the best you will find in the racing genre. Definately a must have.
Kameo- Well, I haven't gotten far into the story, but so far the game is pretty interesting. The gameplay definately has some diversity and the graphics are some of Rare's finest.
Tony Hawk's American Wasteland- There is not much of a difference graphically between the Xbox and Xbox 360 version, maybe some improved enviroments. But the 360 version has some real easy gamerscore achievements and some awesome online play. I personally have been a fan of the series since Tony Hawk Pro Skater on the N64.
Quake 4- Graphics are provided by the trusty Doom 3 engine which still look great on the 360. Though at times, the framerate drops significantly in fire fights. But, with that said, Quake 4 single player has some pretty good gun slinging action in it. The weapons all have the futuristic look to them, as well as the enviroments. I haven't really went into online yet for Quake 4. I have played a match or two, but thats about it.