Casio PX-S5000 looks stunning. Polished finish and keys with wooden inserts on the sides make the instrument look absolutely beautiful.
The new key action feels very good to play. I'm still a beginner so I don't have a lot of experince on the different actions, but this one feels very responsive. The surface of the keys feels very nice under your fingers. Both white and black keys have textured surface which gives a good grip, without sticking to your fingers like Yamaha's entry level glossy keys.
Build-in speakers provide clear and crips sound, but they are lacking punch on the lower register. I guess it is because of the speaker size which is quite small.
What I didn't really like is that the black keys make a quite a lot more sound when released quickly. White keys are very silent. But don't get me wrong, even the black keys' noise is not too bad. But I like to play with very moderate volume so I can hear the difference more easily. Also the key lenght is very short due to the size of the instrument. It makes the keys little more heavy to press near the felt area. They are still ok and it doesn't bother too much.
To summarize, PX-S5000 is a very beautiful and capable digital piano.