A keep if you are a fan, but a rental if you're not.
The sound for the game is pretty impressive especially since the makers of the game took the time to get the actual actor to voice act in the game, which made the game play feel more authentic.
The value of this game truly depends on how much of a Spider-Man fan you are. I say this because, the game is far too short.
I would only suggest buying it if you were a big fan and wanted to keep it as collectors item or as a game to pop into the PS2 when you got the urge to web-sling. If not a big fan and you just want a quick fun time as the web head then you should just rent it.