Overall really good sounds, most of the time I dial up something close to what I'm looking for and tweak it alittle. Good transparency for a unit like this (ability to hear tone of guitar through the effects). Reverbs are a little on the tinny side, and not as dense as say a Lexicon (but hey, what do I want for the $$$? ;-} ). Sometimes distortions are a little washy in live applications (need more clarity & punch). Supposedly improved with later versions. Could use a cabinet simulator to round out the effects field.
One major down side- I wish it had a true stereo chorus (the price we pay for single chip technology). The original tuner (preset 005) is finicky, especially with an electric/acoustic. Not receptive to fluctuations in current- use a power conditioner/spike protector. LEDs/patch window hard to read in outdoor gigs. Has a power out to bypass using the wall wart with the X-15 Ultrafoot- but the mfr didn't recommend using it! The external effects loop in my unit (all units?) is preset to be "on" for every patch. If I want the external effect only on 1 or 2 patches, I have to go through ALL of the presets and turn off the ones I don't want. Doing this to a couple of hundred patches is a major pain! Should be preset to *all off* so you only have to go into the patches you want the external effects for. Overall, very reliable.
Even with its limited shortcomings, this unit has served me well in project studio applications (versatility), and in live applications (control of effects using X-15). Have owned the unit since 1992 and STILL have barely scratched the surface when it comes to using it to its fullest.