It's crazy! I see Usopp on so many people's favourite character lists and I just don't get it. He's annoying, a total coward, and nobody would consider a kid with a slingshot to be a sniper. Give me Luffy, Zoro, and Sanji any day over him.
I even heard somewhere that Usopp was a character that they wanted a spinoff for. First of all, that's a terrible idea (An Ace spinoff would be the best), and second of all, if he was by himself, he'd probably be dead in less than a week.
(The only thing I like about him is the rubber band of doom. :P)