Having just completed this game (in time for its sequel out next month) I can honestly say this is one of the best action adventure games I have ever played. It is almost as good as the GameCube version of Resident Evil 4.
By now you will probably have heard all of this before, but just to reiterate:
Graphics - Stunning, huge environments. Different colours and themes make for the creation of a huge world.
Gameplay - the action is relentless, the puzzles challenging without being frustrating, the platform puzzles can get to you but you persevere because you want to see the next section. Very little backtracking keeps you going.
Sound - ...of the gods! Epic, Oscar worthy score sets the heart pounding, if the visuals aren't enough for you!
Value - the number of secrets and treasures is astonishing. Tried the unlocked God Mode, died on the very first section of the first stage!
Overall - 10/10. they don't get much better than this, I hear that the sequel is though. Frightening!
Please please buy and complete this game before you get God Of War 2. You'll be more than happy you did, it's an exhilerating experience.