Sly Cooper: Thievius Raccoonus is a fun game, although it does have many cons that limit the fun you can have with it.
Now, the music. For most stealth-like games, they would just have clanks and whirls and whistles in the background, or whatever background noises would be in the level. For Sly Cooper, however, they have very fast-paced pieces of music for some levels, and the battle themes (even though they are almost the same for each 'world') get you in the mood for a fight.
The graphics aren't bad at all, they're actually pretty good. Being cell-shaded, they can do almost anything with the characters. Which they do, actually. The cutscenes are in a comic-like format, with cell-shaded-like drawings. This gives it the feel of a slideshow movie, which can be very entertaining for some, but some will find it flat-out annoying.
All in all, Sly Cooper: Thievius Raccoonus IS a fun game, but, unfortunately, it doesn't appeal to most of the general public's fantasies. When you try to make a stealth game, you have to make it more of a darker setting, not so happy and perky all the time. Think Splinter Cell.
Other than that, it's a good game. If the makers of the game (Sucker Punch) had thought to have it in a creepier, scare-you-out-of-your-socks-environment, this would have gotten a higher grade. But, if they keep this up, the 'Sly' series will most likely get even better. Well, time to wrap this up. If you want to try this game, go ahead and buy it. You won't regret it, if you do.