This game is overlooked because of it's graphics, but there is alot of content here, and it costs next to nothing.
Graphics wise, Runescape is a huge let down. It's graphics are one of the reasons it gets so much negativity, but the poor 3D-ish graphics are what allows it to run from your browser, with no download and fairly smoothly on a 56K moderm. These graphics are slowly being improved and will probably be overlooked by the user once you get into the game.
The sound in the game is of pretty low quality, cellphone ringtones would sound alot better, and they tend to get reused alot. All fire spells use the same whooshing sound and all teleport spells are basically the same, but there is still a large list of background music to listen to and choose from that you unlock as you explore the world of Runescape.
There are weekly updates, although most are rather dissapointing. It seems Jagex is aiming for quantity rather than quality. Still, there are alot of good entertaining quests and skills. Just to name a few, there is Agility, Woodcutting, Strength, Range, Magic, Herblore, Fletching, Cooking, Fishing, Hunting and ofcourse the amazing Firemaking skill. All skills are getting frequent updates and new ways to train and use them.
Lastly but not least, the value. When compared to games like WOW Runescape is a very cheap game, especially since it is rather in depth. There is also a Free World with a large amount of quests and skills, so you don't have to pay at all, although the small monthly fee will unlock a huge amount of updates.
Overall it's a good (and cheap) game if you can overlook the graphics.