It's not the graphics that make Runescape a poor game (as some have implied previously); it is the core gameplay.
I mean, Blockland isn't exactly next gen, but it remains a good game because it features good gameplay with lots of variety. On the other hand, Runescapes gameplay is plain and uninteresting. It's community is also rather poor.
I used to rather like the game until I realised that I wasn't really having fun.