The yamaha FX500 is full of great reverbs, delays, chorus effects. It even has a compressor! But the overdrive and distortions are absolutely the pits (IMO). I think this was used a lot on the band SLowdive's Souvlaki Space Station. If you're a tweakster you'll love it!
I admit that I don't want to program this stuff. I just bought it because I love Slowdive's sound and guess what, they used the preset 39 and 40. So plug a strat add some reverb, then to add some reverb and at the end of the signal don't forget to add some reverb and you have the Primal sound.