As usual, Boss has made a quality pedal that will last from one generation to other. However, it has some minor flaws in my opinion in its design's usability compartment.
I like the sleek and industrial looking housing, reminds me of Ibanez ToneLok series pedals from the early 00's. On the bad side, the powder coated metal treadle makes the use slippery when not wearing shoes. The bottom has the unfortunate four little rubber pads on the corners that I find extremely irritating; nowadays people velcro or dual lock the pedals into their boards and these kind of solutions make it a notch harder.
Tonally the pedal has both classic wah sound and its own thing going on. Both settings sounded pleasant to my ear and had good range. The pedal worked well on guitar with anything from E standard to B standard tuning. I have no experience on how it reacts with bass, I never tried it out.
Putting the mode selector switch between the in and out jacks on upper side of the pedal is mildly annoying, since it takes a bit fiddling to get there with your fingers, especially on crowded board. I liked the way on/off function was designed, but in practice it was a bit difficult, since the switch needed really stomping on it to activate and deactivate. On the plus side, the treadle was pretty easy to leave in cocked position. Slightly small area of operation needed some adjustment, if used to classic Dunlop or Vox wah operational movement range like I was.
All in all, I liked the sounds and the looks, and slightly downsized chassis compared to classic Dunlop / Vox sized wah was a good thing. However, I ended up selling the thing because of the somewhat minor but still irritating enough issues with operating. It's a quality piece of work, though, and if you care to mod it a little for added grip and removing the pads on the bottom, you can make it work.