I didn't want a heavy piano to haul around, found this reviewed in SOS. Case is plastic, build feels a bit cheap (you can tell jacks are mounted on internal circuit board and are probably a bit delicate), but keys feel solid and action is very piano-like, but maybe a little too stiff for some. But I like it.
The two main piano sounds (Grands 1 and 2) seem to have a pretty rapid decay, may not be great for ballads. But other sounds are good, I find the "mono piano" to be good. Not an issue if you are using an external sound module or computer. Has USB, MIDI, audio in and out, two headphone jacks (mini-jacks, I wonder why they decided on that?). Reverb is a bit anemic and I haven't yet figured out how to program that or other more esoteric settings such as "damper resonance", but it's supposedly in there somewhere. The damper pedal it comes with is useless cheap plastic, you will definitely want a sturdier one. Casio's three-predal unit (which supports half-dampering), is only available with their stand, which I wouldn't want.
I paid $740 including shipping. I could of gotten a Yamaha P90 or P95 for less I think, but they are much heavier, although the grand piano sounds are better IMHO.
No modulation wheel which is a shame. There is a modulation button which simply switches between two preset modulation levels, can't really see the point of that.
Memory card supported but only 2 GB max - I wonder why they crippled it with that limitation?
For those wondering what's the difference between the PX-3 and the PX-3S, this is from Casio:
"The PX-3 sold through much faster than we expected so they ramped up production again. Since these will not say "limited edition" on the front panel they had to make other changes which include officially includes the SKU number, so they added an S for stage. They did change the color of the LEDs to red and it no longer includes the letter from Mr. Kashio."
Added this after a few weeks of use:
A big shock to me was the fact that there is midi in and out and midi over USB, but you can't use both at the same time! In other words, even though it has USB it is NOT a midi interface. Once you plug in a USB cable, it disables the midi in/out completely. Silly, considering that even sub $100 M-Audio keyboards have a fully functioning midi interface built-in.
Another silly omission: there are lots of GM drum sounds, but no drum patterns built in, and no metronome. When I saw the "tempo" and "tap tempo" buttons, I thought there would be, but that is just for playback of midi files from the card reader. The lack of a metronome is a drag, because, if you want to practice with headphones (so as not to disturb others), you will have to plug a metronome into the audio-in jacks - but you will then have to unplug your CD player or computer that you might want to play along with. Not very convenient.
One other thing: the foot pedal is a cheap plastic switch. unfortunately, the polarity that Casio has chosen seems to be the opposite of the standard Yamaha and Roland pedals out there, so you either have to buy a Casio pedal if you want a good solid one, or find one with reversible polarity, because you can't reverse it in the software.
Shame on SOS for not mentioning these shortcomings.