In an era where MMORPGs are a dime a dozen, this is the proverbial "Diamond in the rough."
World of Warcraft truly surprised me with its genius. The developers took out a lot of the stuff that makes MMOs drag on and on for what seems an eternity (ala EQ). I progressed into the higher levels faster than I have in any other MMO, and at the same time continue to find new content just about every day.
While reaching the level cap did not take as long as I expected, there is not a lack of things to do at the end. With all the raid dungeons, mass PvP maps, and the scripted end-game content and quests, I still have my hands full after a year of play, not to mention the fact that Blizzard adds new content with each patch.
There are still some mindless activities that this game's predecessors included, but that is to be expected with an MMO. There will always be "the grind," but at least in this game it is very tolerable and you always feel you are accomplishing something.
This game is geared more towards those of us with a life. Because MMOs are notorious time-sinks, most people don't get into them because they simply can't devote that much time to anything other than work/school. WoW actually rewards those of us who can't play for 8+ hours a day by giving you a rested experience bonus for NOT playing for a while.
Now, don't misunderstand me. There is also plenty for those of you who make playing an MMO a lifestyle as well. There are raid dungeons that can take a good 6 hours of straight playing to accomplish, and only the hardcore will obtain all that the dungeon has to offer.
So, all in all, WoW has something for everyone. If you have never played an MMO, then this is a great game to start on. If you have played an MMO before, then you will find a great deal of entertainment in the world of Azeroth.