Anyone who says that Runescape sucks compared to WoW, Guild Wars, LotRO, or any other online game fails because you can't compare them.
For example: WoW is a game that is a couple of Gigabytes big, has been made by a huge company and you have to pay per month... and what is Runescape? - a browser mmo made by a pretty small company and at least the half of it is completely free to play.
So... you really can't say that Runescape sucks because the developers did a pretty amazing job in making such a large game, which is freely playable in a browser.