The anime was frankly shite but the manga is very epic (still on going but will be ending soon). The anime stops before you're introduced to the good stuff and then gets even better. Of course the director was aiming for a different direction but yeah. We actually get to see Kurono get the character development he deserves and evolve into a hero. There's a lot of bad assery I'd like not to spoil.
Looking forward to Gantz the movie parts I and II, should be better than the anime. I hope we get a better series after the manga has had its run.