I bought one of these about ten years ago and really liked it (yes, it was sold. Just like most of my gear). The bypass isn't great but it has so much going for it. The operation is simple and there are plenty of good sounds within this unit.
None of the distortion sounds are good. About half of the presets you will skip over within seconds. The compressor has the ability to be a bit crunchy in a very digital way that sometimes works but mostly doesn't.
But the modulation.. oh, the symphonic modulation. It's fabulous. If I want reverb from a rack unit of this era, I'm jumping on an Alesis Midiverb II, Quadraverb, or one of the cheaper Lexicons like the Reflex. The biggest strength of the Yamaha units like the FX500 and SPX90 (if you're not into the reverse reverb) is the modulation options.
To start with, I'll go through some of the presets I like. As ever, it's straight DI recording with a small amount of compression to balance out the audio at the end supplied by the Kotelnikov compressor plugin.