Runescape is okay, but it's too boring, too repetitive, and the community sucks.
Like Wedge said, picking chicken feathers off the ground isn't always gonna be fun. The funny part of being able to attack a unicorn fades away pretty quickly.
The combat is "click, wait for them to die." In Mabinogi, you're always watching to see what skill you can use to hurt them most. In Runescape, you go eat a cookie. Not fun or interactive enough. The same goes for everything else: mining, woodcutting, you name it; click, forget.
The community is FAR worse than BL's. Here, we get the occasional idiot (whoever happens to be most hated, usually), but that's nothing. In runescape, you can't walk 2 meters without running into some 40 year old man saying "omg im a gurl wana be mi bf", or finding some 5 year old that can't use a keyboard properly. The maturity level is just far too low for the game to be fun.
TL;DL: Boring and idiotic community.