Battlegrounds is supposed to turn WoW into Warcraft 3. What I mean is it is the war scenerio with units, bases, resources, all in the WoW environment. To get resources you have to do quests inside battlegrounds ect. This is all going on while a gigantic battle is raging on.
Read the full battlegrounds preview (parts 1 and 2) and you will get a pretty good idea. It is basicly 40 horde vs 40 alliance.
This is only for the 1st battlegrounds though. From what I understand they are going to do things differently for each one.
And as eViL said, PvP is a lot of fun. You gank, you get ganked, then you get your guild together and raid their towns. It is a lot of fun. You can avoid battle with mobs if you are smart. If someone of the opposite faction wants to fight you, you are either going to fight them, or not quest in that area for a while.
Besides, on my server there isn't much corpse camping. You just die, and they run away.
It isn't like you lose anything from dying in PvP anyway unless a mob gets the last hit.