I play and record professionally, and bought this for quad-voice chorus and flanger effects only. I play acoustic and alternative, using an Ovation Specialty through a Matchless DC30 with a Matchless Hotbox pedal, tube reverb, and tube compressor. Those two effects are great, but this unit is difficult to ground properly to get rid of the noise, and it makes your signal brighter even when completely bypassed. The quad-voice chorus is great, and you can select four or five different waveforms for the flanger among like 6 other parameters (as for chorus and phaser as well), which lets me emulate the tones of the ADA Flanger nicely.
As for the other effects:
Delays-------good for a digital delay
Reverbs------pretty decent, but it's no Lexicon or tube 'verb
Compression--terribly noisy and ineffective, no useful parameters
Tremolo------actually pretty good
Phaser-------pretty good and smooth-sounding algorithms
Chorus-------can get tinny, but if set properly, can be quite good
Flange-------swoopy-sounding, but purple and colorful
Wah----------the pits, absolutely terrible
EQ-----------four-band parametric; GREAT
Distortions--all are noisy, brittle, & digital, no tone parameter
Note: for the two effects I use it for, it sounds great, but there's still some noise, which in the studio or at home is not a problem. There's always some background noise on the flanger, but that's not terrible, and can be worked out of the signal with a few minutes of setup if you don't like that sort of thing. These are not the best modulars out there, but they sound great for the few bucks I spent, and sound very nice on recordings (a big part of that is the amp warming them up).
For all that, the modulars can be quite lush in their more subtle settings, but I'm not much for much processing anyway, so it works out. If you want usable distortions, compression, or think the expression pedal can be used for wah-wah, you'd best get almost anything else (Roland GP100, Rocktron, Lexicon, Digitech RP-20, etc). The worst fuzz or overdrive pedals I've ever encountered were so far better than the grunge or overdrive in this unit that I couldn't describe it. The compression should just be labeled "noise" because it doesn't compress or level, just adds line noise. The "wah" is a joke. The "heavy sustain" distortion, if it weren't for the noise, might actually be rather usable--a mellow, fuzzy thing.
Recording direct with this thing would be a sick joke.
All effects, even the modulars, need warmed by a tube amp, else it sounds metalic and (gasp!) digital. And you have to work to kill the noise-factor without using the horrible noise gate.
These devices are problematic. The first one I had when I began playing had problem after problem until it died two years later. This was under my college guitar instructor's desk for six years, controlled by MIDI only, never by direct use of the pedals, so it's still mint, but I don't anticipate it staying in that condition. I'm going to be very delicate with it.
For $100 used, it's all I wanted or needed it to be. Considering how well it does the ADA Flanger thing, and for how good the stereo 4-voice chorus is, with programmable 4-band parametric EQ, all stored in memory, it was worth it. I wish it had proper grounding, or that it had a HUSH circuit rather than a bad noise-gate.
For my purposes, it's the best choice for my needs and not wanting to spend a ton on two great chorus pedals and a great flanger pedal and a few EQ pedals, or even spend for a really good processor. For most people's uses, this would be a terrible mistake.