I don't know if it's my computers USB drivers or the ESI unit that is at fault here, but I was getting constant Blue Screens at first when using the device. It still crashes occasionally and loses sound, no blue screens for a while (they only seem to happen if I connect the device while the computer is turned on).
Sound is very good and clear. S/pdif works without problems with my Kemper Profiler.
Overall a good alternative if you need nothing but D/A and s/pdif recording. But not for much more money I'd suggest getting the Focusrite Scarlett 2i4, much more stable drivers and more i/o (and better customer support).