I haven't heard anyone saying it doesn't deliver, only that there is not much in the box
Makes you wonder what all that other stuff is doing in all those other boxes. I have two amps, a preamp and a DAC on a plate in my speaker box, which is probably smaller than that amp. And it delivers in spades. But the key there, I think, is that it knows exactly what it will be up against in terms of speaker load and doesn't have to be over-engineered to drive multiple drivers through crossover networks into loads that can get heavy...and downright weird. If you know exactly what you're building for it is quite an advantage.
Tim