The build quality is OK, although on my unit one of the potentiometers was non-smooth out of the box.
The analog signal path is great, sound goes through clearly and without noise. However, the diginal USB conenction is disappointing. DAC/ADC connect only to the main bus and can do at max 48Khz at 16bit. 16 bit is not quite enough dynamic range, even at amateur level. More disappointingly, playing music via USB interface vs an external DAC connected into the analog input of the same mixer one can clearly hear the difference (and I'm no audiophile).
But at this price... I would buy it again...