Just got a JX8P a few months back...Known issues with them is the aftertouch being nearly useless unless an insane amount of force is applied and it's cranked. This can be fixed by cleaning. I've hear of a few people complaining of stuck keys, but for a 25 year old synth, that's bound to happen.
I use mine without the PG, and though I would prefer it, it's not a deal breaker...I've never had an issue with MIDI either.
As far as the sounds and programming, the sounds are all over the place. You can do weird FX/Drone, lush pads, EPs, thick basses, MASSIVE leads, and great brass. In terms of sound, you can make it whisper quiet or just as impossible to stick in the mix as any memory moog. Programming is fairly straight forward, if not a menu dive, but in comparison to other synths I've had to menu dive on (Alesis Micron), it's a breeze.
There's a lot you can do with modulation like x-mod, two sync types, and a nice LFO section. Filter is nice and warm. Oscillators are a little on the harsh side and have a digital quality to them, but still resemble analog oscillators. You can route the two EGs to volume, filter, and pitch, which is a nice thing to have on such a cheap synth. Quick access to the portamento time which gives you the ability to play with that during performance for dramatic slides.
Lots of play modes too. 2x single poly mode (2 osc per voice) 2x unison modes (4 osc per voice) and 2x solo (or mono) modes, one being 2 osc mono or 12 osc mono.
All in all, I got mine for free, but if I had to pay for it, I would gladly shell out...this thing is great. One of those underrated synths that people ignore because they're not knob laden or being slobbered on by some famous artist.
32 MU modular system, Electribe (EA-1 and EMX), Microbrute, Nord Lead 2x, Blofeld, MS20, AN1x, Poly 61 (x2), JX8P, Split-8, DX7, Alpha Juno 2, microkorg, Conn Electric Band, TR-505, Ace Tone FR-3, Monotron Delay, Beatstep