Cralor if you have look at my 3.3 thread I had a play with this.
First things first it does not come turned on by default.
You need to click a few boxes in the Interface options to turn it on.
You can also easily turn it on and off on the map itself if you don't want to look at the quest tracking features.
Another thing - it only does the basic "here's where you go for this quest". I don't think it can handle any quests more complicated then that. Escort quests would probably stump it as would quests requiring you to use objects in certain places or using objects that drop on other objects.
No what I'm excited about is the fact it puts there where to go to turn in a quest. If this can be exposed in the wow addons api it means that quest addons would become more efficient