You will find a fantastic explanation here:
http://www.gamedev.net/community/forums/topic.asp?topic_id=123169&whichpage=1򤻢The author compares ABT, BSP and octrees. He writes that a binary adaptive tree is fast and powerful and delivers something between BSP and octrees. It can be used with dynamic content and does not need pre-calculation.
But the re-organization of the moving objects can make it inefficient unless you re-calculate some nodes on the fly.
But for indoors you have to use it in combination with portals or occlusion geometry. Otherwise it will not do very efficient culling for this sort of environment.
Meshes in the nodes and leafs of the tree will be handled the same, no matter if they are made from blocks or from models. But I dont know about the differences of the internal rendering, materials, collision detection and other factors that can make a difference between blocks and meshes.
So in the end it depends on your project. ABT will manage and render an open scene quite well, but will have problems with bigger indoors.
