With Riley, it's helpful (and important IMO) to distinguish between "enjoy in the game" and "like the character." I think she is a lot of fun in the game, but as a character I'm not really attracted to her, and don't think I even like her that much, even as a friend. Some crazy is fun (I adore Nova in Eternum, even if Annie edges her out for my top spot), but too much is too much. The infamous helicopter scene is fun to watch, but not (again IMO) hot.
The problem with "fun in the game but don't really like her" is that it kind of breaks immersion--if I'm making those kinds of distinctions, I'm just not in the game.