@Slimebeast look at his Avatar!
I played it at a friends house (I've a PS3, he has a 360) and my experience was mixed.
I thought the graphics looked better than Halo 3 and everthing 'felt' sweet about playing the game, both in SP and MP.
However, after a while we both felt that it didn't feel like it offered much more than Halo 3 itself due to that strong similarity.
The SP was fun but didn't seem as interesting or improved as say Gears 2 vs Gears 1, and the MP, while great, at the same time didn't seem to offer than much more than Halo 3.
The game is clearly very polished and plays terrific, but I can understand why some would feel it just doesn't add enough new elements from Halo 3 as you might hope.
Try to be reasonable... its easier than you think...
