I got one of the first run of Catalinbread Perseus pedals today. Luckily, Howard's demos are already so good I'm not under a lot of pressure to try to do the Perseus justice in words. For anyone who doesn't already know, the Perseus is a fuzz with two switchable sub-octave tones that you can blend with to the fuzz tone to taste. There's also a "Cut" control that controls the amount of low end in the fuzz itself (not technically a "presence" control, but that was kind of how I was using it).
You can turn the sub-octave off entirely and just use the fuzz (it's pretty decent; kinda spitty and gated, could be used on its own for rhythm if you wanted), but I think it's safe to say that the point of the Perseus is the sub-octave blend. If you've ever used an octave-down effect, you already have a pretty good idea of how it works. What makes the Perseus special is the number of tones you can get by choosing which sub-octave (I or II), the amount of octave, the blend of fuzz and octave, and the cut of the fuzz itself. You can get "barely there" following bass lines, huge organ or synth type tones, smoothly-tracking or glitchy, etc. There's really a lot of range and you can easily and intuitively dial in pretty much anything you can imagine within the limitations of the effect itself. I found that running a relatively tame Perseus tone into a high-gain fuzz pedal (like the Zero) added even more possibilities for synthy goodness and got real awesome real fast (however, the Zero definitely cut out a significant amount of the Perseus' low end; I'll have to see if the Supa Tone handles the low end any better).
I think someone asked in another thread if the Perseus can handle chords. Uh, that's a NO. Unless I'm missing something, the Perseus is all about single notes, unless you're going for a wash of glitchy noise, which the Perseus can definitely pull off as well if you want.
I was playing through a single 12" speaker. It wasn't farting out or anything, but I really need to try the Perseus through a larger cabinet SOON...