It may be true that the build quality seems surprisingly good for such an inexpensive box, but that can't possibly compensate for this sound.
To be frank whatever algorithm is used for the pitch shifting in this pedal has to be rewritten. As others have noted, the added octaves sound out-of-tune most of the time. Even on those notes where it didn't sound out of tune, there's a very noticeable fluttering effect, probably due to the windowing used for the pitch detection.
Another reviewer commented that maybe that's standard fare for octave pedals. Let me just say, I've never heard this particular problem before, in analog or digital pedals, nor in any software. This is easily the worst-sounding octaver I've heard anywhere.
I've tried a few Mooer effects in the past, and they've all sounded above-average or at least acceptable for the price range. But not this one I'm afraid. Back to the drawing board. Will return the one I ordered for sure.