Well you won't get 100-150W out of it. 45V rails is pushing it. Maybe 25-35V. TIP41 makes a lousy VAS. Diodes for biasing mean it'll run largely in class B - and the instructions dont say anything about mounting them on the heatsink with the output transistors, so it'll likely blow up due to thermal runaway under load.
With just a few more parts you can build a stable, reliable amp that doesnt sound too bad.
A poor circuit, drawn in a peculiar way which hides its operation. It would suffer from crossover distortion (from the crude diode bias), output DC offset (from the mismatched bias resistances for the input pair) and a big thump on switch-on (due to large input capacitor). Bass response stops at 20Hz due to the 100uF capacitor in the feedback loop, but as this is an electrolytic it is subject to low tolerance so a stereo pair could have LF points a long way apart. HF response is not defined at all, so there may be a risk of instability.
It looks like a first attempt by someone who has just come across the standard 'op-amp' topology, but has yet to really understand it.
Some little man in a Chinese workshop is probably tooling up to make these, as we speak. Put it in a fancy polished box and morons would buy it off ebay!