Zoro has no personality other than to take up time for fangirls to squeal. Maybe that sort of character is fun if you've not read more than five shounen, or if you're just plain a faggot, but otherwise you just want to rip out pages involving Zoro.
I'm picking on Zoro, but Luffy, Sanji, Nami, Usopp, and Robin are all pretty fucking horrible. Brooke is still fun, but he's getting tiring already. Franky and Chopper are fine.