Still have to play the first one. I'm not a huge fan of the genre, but X zone always caught my attention. And SEgata Sinshiro...
The game's really cheap now, and it's quite fun, so I'd say give it a go. Just uh, play it in small bursts. The game kinda gets overly repetitive if you play it for long periods of time. I usually only do a stage or two every now and again.
I'm never usually a fan of SRPGs, since usually they wind up being like Disgaea and being way too complicated for me (too many numbers to keep track of, tons of options, just feels overwhelming after a bit). Thankfully, PxZ is about as simple as you can get with an SRPG.
PxZ2 seems to be spicing it up more and getting rid of the cruddy elements (like DAMN REINFORCEMENTS) so I'm super hyped for it.