Don't take me wrong; I love this game and you'll do if you are into heavy metal since the world and the plot revolves arround the stuff seen on molst old school (DIO!) metal albums' booklets.
Also the game has the kind of charm like, let's say the past generation "beyond good and evil" game, and you'll hear awesome tracks while seeing a reel of jokes about the hair metal-heavy metal world. But the good part ends here.
This plays like a sandbox but instead of jumping you get hack n slash style controls, with combos and such. You can drive a car (hot rod) but don't expect variety on vehicles or weapons because the core here is to slash with the axe, long range attack with the electric (thundering) guitar, block andinteract with allies like the elika moves in prince of persia but not so deep, just 1 attack for eacht type of ally. Even side missions are repetitive to death and the world is plain boring to explore since the only reason to do is to find unlockable dragons (you get a character enhacement for every 10 dragons found), portals to ozzy (store), extra tracks for the car and few awesome places to look at, like motors merging with mountains, giant stone swords and the likes.
I didn't give multiplayer a try (yet) so can't comment on this. Gameplay is good but not so deep. Music is good. Graphics are so so, since cartoon style is much forgiving than a more realistic approach but still has some detail in close up cinematics.
My rating, a 6 or maybe a 7 just for the wrapping, but the core of the game should be rated mediocre, wich ain't good nor bad.
Buy it half the launch price or cheaper and don't expect much of it and you'll get a great game with a lot of charm and humor, two things hard to find in games nowadays... unfortunatedly games nowadays have a lot of other stuff in spades that this game lacks. Keep it in mind.