I don't use it much. I'll probably hang on to it, cuz you can never have too many processors, but it's far from a vital part of my kit. If you're looking to emulate that 80's teenage Van Halen cover band sound, you might dig it. Not sure what version this is. 6 Sound quality really varies depending on algorithms used and how strong a signal you feed it etc.
Knobs do get scratchy if it gets dusty.
Bought it in '91, they've discontinued this model. It's a decent rack for the beginning guitarist to get his feet wet as far as effects racks are concerned. This was before the days of Nirvana. Everyone, regardless of the gear they used, sounded exactly the same. I used it with a Fender solid state amp and a variety of guitars by Ibanez, Washburn, and Fender.