I bought the Blueboy from a band colleague after extensive testing.
Apart from the Master Vol and the Gain knobs,
there are controls for Bright, Tone, Mids and Char.
Mids and Char are not that useful for the Bassplayer,
but the Tonestack of the toneknob is awesome and the boost for the highs is usable, too. The Tone knob does treble cut + bass boost turned CCW and vice versa.
There is absolutely no loss in the low end, with the Tone knob set in favor of Bass, even the low B gets a nice boost.
The OD is quite warm and very responsive to how hard the strings are hit. It can add just a bit of girth when played softly and start to growl when hit harder.
All in all a very nice overdrive with potent tone shaping potential.
Quality made and the little knobs stay where they are, even when you put it in the gigbag.