If there was ever an iconic plugin, this is it. A cult following for sure. It seems like it’s been around forever, and was the “I swear by this” plugin for a long time.
It’s been a while since there has been an update to this, but that might be because there is not much to improve on. You may have noticed most of the plugins I own are from the “big-name / expensive” guys, but PSP is that rare indie exception.
One review of this says it has “a lovely warmth and thickness”. So, it’s like throwing a bedspread on your sound? OK, whatever. You can adjust the drive, which adds harmonics, and you can EQ with it. I’m sure that is lovely and all.