To be a bit more clear, the detonation is racing around a circular track in one plane, but the net thrust is in the direction perpendicular to that plane. Fuel and oxidiser are continuously pumped in all along the track, dropping to ~0 after a detonation and rising afterwards until the detonation front arrives again. Since you don't have to pump into a continual high pressure deflagration like in a conventional rocket engine this looks like it should be easier in terms of pump power.

Rocket engine efficiency, like all heat engine efficiency[1], governed by the difference in temperature between hot and cold in the cycle. Because at any given point in a detonation engine the combustion engine only comes in pulses it can reach temperatures that would otherwise melt the rocket engine. That's true of regular rocket engines too, which use active cooling, but seems more true of a detonation engine. And I would guess that the exhaust, already being supersonic, needs less of a chock on the de Laval nozzle to ensure laminar flow.

[1] Strictly speaking this only applies to combustion rocket engines. An ion engine, for instance, is a rocket engine but not a heat engine.