Starting playing in November and now I play nothing else but...
The quests are great and there are plenty to do, no matter what level you are. The world is huge but joy to walk through and take in the sights. The cities are spectacular. Very well thought out.
Being able to create many characters is another plus, although I suggest limiting yourself to only 2 or 3. There is so much to do in the game that you'll never get bored. I"ve spent countless minutes just asking myself what I want to do next!
One of the most surprising aspects of the game is how Blizzard keeps it entertaining for the players. There is always something new to go do or see.
For entertainment and play value this is the best game out there.