Agree with Futon on the basic concept but general idea is:
Short = manouverable/agaile, good climbing
Low BB = good climbing, stable – grounding issue managed by being short/big wheels (think SWB landrover)
29er = good roll, bump compliance
laterally stiff = good power stansfer
vertical compliance = comfort with 29 wheels
Truss fork = stiff, accurate,
geometry(trail + head angles) = means stable but quick steering
big tyre clearance = comfort
rear weight bias with seat/bar position = good control, effective downhill even with rigid forks as you can hold the bars lightly and guid the front because your weight is not naturally over the front so upright
riding position
BIG front tyre means you can bomb rocks on a rigid bike whilst maintaining steering accuracy (doesn't track into gaps) and not beating the hell out of your wrists (tyre runs at 7psi) whislt also rolling over most obstacles because of the size of the tyre (3.7 wide about 80mm tall)
I LOVE the big tyre, especially in the rocks but the traction is brilliant even on normal trails at the expense of slightly slower steering.
Futon, if you want to hook up for a ride someday you can borrow my big wheel (Phil Wood one 2 off hub, 70mm speedway rim) and see if you like it before you take the plunge.
I don't have my bike yet, waiting for Jeff to finish it.