Just fooled around with an XW-P1 at the local Guitar Center.
It doesn't suck at all. In fact, the full size keys and the keybed are better than what's on most synths and controllers they're selling these days.
I actually experienced a small thrill: Casio has included a Theremin sound . . . and it doesn't suck at all. That alone could save me $300 for a Theremin and countless hours learning to control it. I've never encountered a Theremin sound on any synth. Loved that.
There was also a muted guitar I would definitely find a use for.
A quick comparison between the piano and other usual suspects like Korg M50 didn't reveal the Casio as decidedly inferior. They both needed some EQing, but in the right hands, I imagine the sound would be quite acceptable.
The arpeggiator seemed creative enough.
The thing was easily worth $500.
It was a little hard to figure out if the drawbar controls also function as MIDI controllers, kinda looks like they don't, cause you can only switch between 1-8 and 9-16 . . . but I could be wrong.
The only negative was not "cheapness," it was the somewhat inscrutable legending that didn't make it easy to navigate for a new user; some would say that just continues the Casio lineage. However, that's why they have manuals.
I suspect I'm in the same boat as a lot of you: go for this or go for a dedicated controller like the Axiom Pro? True, the Casio is not a keyboard controller per se, but it can obviously perform basic controlling tasks perfectly well. You just won't have start and stop buttons to control a DAW or the ability to recall editing modes for VIs. I think if someone put a gun to my head and asked me to choose, I'd probably pick the Casio and sacrifice controllability for a boatload of sounds, arpeggiations, and the ability to play without a computer and take it out and play live.
Also, from a dollars and cents viewpoint, I have always felt the Axiom Pro was overpriced . . . and the Casio is clearly a huge bargain.
Those are my preliminary observations.