This a phenomenal tool when used at maximum tolerable levels. I've been using it Charlie Francis style (aka.. 10 reps max with 1 min recovery on large muscle groups).
The improvement in strength and endurance in my runs is through the roof. You can actually feel the increase in power in each step.
I believe it increases the neuromuscular coordination due to the increase in muscle fibre recruitment. Whatever that means.. it works. Anybody else have stories when using it in max strength mode (as opposed to injury rehab)?