One of the best Sega games ever...
The game itself looks awesome, being one of the first games to use the cel shading style and put its to great use with its theme of grafitti. The gameplay itself creates more of a challenge, it takes a bit of getting use to, but you'll be tagging soon enough.
Only real complaints with the game being the camera angle and some people will nitpick bits and pieces of the soundtrack (like Dragula), but besides that it isn't enough for you to pick up this game, especially if you don't have it already.