I had a Demon Hunter, Barbarian and Monk all to Hell, and like Triple said, it gets frustrating, and redoing the same zones over and over again got boring, so I quit playing.
The idea of the same zones, just harder is fine 1 or 2 times, but by the time you've gone through all the acts 3 to 4 times times over 3 or 4 characters it's monotonous.
For a game go gear centric, there's nothing interesting about any of the gear visually. Beyond looking at the stats I don't think I ever noticed appearance wise anything interesting about any of my gear. maybe glowing swords, but most swords had some glow by the time you started getting decent gear, so it lost it's cool factor.
I'm sure when you really get way up there there is some cool looking stuff, but I got bored long before I ever made it there. And I had enough crappy PU groups to realize I wasn't going to party unless I knew the people.