Has to be one of the greatest animes out there.
Don't let the 90's animation and clothes fool you, it is timeless and the first anime series that I had to own once I had watch it on Adult Swim all those years ago! I have probably watch the entire series 10 times completley and I still enjoy it as much as the first time I ever watched it. The first saga may seem alittle slow but once Yusuke gets in to the swing of things the series picks up and never stops.
If you enjoy any of those other classic animes like Dragonball Z then Yu Yu Hakusho is a must see.