I've had a month of getting to grips with this and I bloody love it.
A good clean first and it's in really good shape.
As far as I've found so far everything works.
I know it's kind of pretending to be a real keyboard, and most of it is way out of my understanding, but I'm amazed at what this thing can do.
I'm still stuck in the early 80s sonically so it's sounds suit me just fine. The pianos and electric pianos are really good, it has it's own versions of most the big names, even other manufacturers trademark sounds, the strings are good too. Loads of sounds I'll never use as well.
It has an in depth synth section which seems fairly easy to create your own synth sounds as well as just tweak the onboard ones, and a sequencer, the bits that interested me. It seems that you can use it like a recording desk but I haven't got into that yet. Lots of features like polyphonic aftertouch which baffles me (something to do with midi I think) but hints that Casio must've meant business with this keyboard.
I no pianist but the pianos are that good that I've found myself coming up with a lot of new stuff that I never intended to. Anything that inspires you to write new music must be good, right?
I've bought far too much gear this year but this is one of the best things, and only twenty quid.