Just finished my first ever playthrough of Rez, and it has to be easily one of the best games i've ever experienced, right up there alongside, Zelda: OOT and Final Fantasy 7. I think I just really 'got' the game, despite not being a fan of electro music, the art direction is the real winner, its stunning. Then underlying this is a self indulgent depressed computer program who knows the real 'truth', what this truth is, is dependant on your interpretaton of the game, my take on it was the inhererent loneliness humans suffer from as the realization sets in that you are alone in yourself and always will be and this has perhaps dawned upon this conscious AI, seeking some form of 'truth' or reason for its existance and cronic loneliness it comes up short, leaving it in a cold and depressed state, hence the final boss level and battle being about creation and spirtualisation.
So to conclude awesome game, if you havn't played it yet do so now, its the best on the 360 right now.
P.S. Stage 5 is my new favorite level in all of gaming beating out Goldeneyes Facility level.