From what I've read and some which I planted, the hybrid poplar needs pretty good soil, needs to avoid deer, needs good rain, and it will grow well and fast. It also will stump sprout after being cut, but this can be a bit frustrating because lots of shoots will be sent up -- need to thin out the sprouts. I assume it has about the same btu content as other poplar, aspen, etc., which is about 1/2 that of hickory or white oak. I think it would be a good choice for a short rotation crop where use of the rounds with minimal splitting was the goal. Probably also would be good for a gasification boiler which does very well on 4-5" rounds/splits.
Some don't like these low density woods, think they are too much work. I burn aspen and low btu pines nearly all the time, and for me, all wood is good heat and usually is good money saved, especially if you have your own land.