World of Warcraft is one of the most addicting games you'll ever play. Blizzard's first foray into the MMORPG genre puts you in the position of a member of one of 8 races and 9 classes.
This is an MMO that truly appeals to MMO newbies and veterans alike. The gameplay is very addicting and fun. Even if you are not an MMO fan, give WoW a try (especially if you were a huge Diablo II fan like me... you'll find that WoW is much like DII... just bigger!).
There are a few downsides of course... first, I haven't been completely impressed by the customer service from Blizzard. I thought they did a much better job with StarCraft and DII.
Secondly, the servers are not as good as they should be. Problems WILL happen and bugs do occur (way too often).
Finally, there's a monthly fee. However, you WILL be getting new content (and recently, content has been coming out at a very reasonable rate).
However, the gameplay is amazing enough to make this game score over 9, EVEN considering those two things. Blizzard knows how to make games that are fun to play. WoW is no exception. It's currently (as of July 15th) 8th on my all time list.
If you're searching for a new PC game to put a lot of hours into, WoW is for you.