I believe D-Rex has over 100 sounds and over 100 movements. What I enjoy is the randomosity and unpredictability of the movements. It's easily seen if you stick two (or more) D-Rexes into a mode like prank mode, and then when they're out of the mode they may turn their heads in the same way, or they may not, they may make an interesting sound, their eyes may go nuts, etc. and it seems like there's a different sequence each time!
Like IMR said, it is thirty movements in sequence. You can play back these movements as wished (oh, and BTW IMR, they cannot move their hands).
About the skin. I think it feels pretty cool, though not quite as textured as Pleo's (though neither of them exactly feel "reptillian"). When you first get one, however, they have a thin coat of some sort of gooey stuff on them (which I fondly refer to as "embryonic fluid"). That's part of what makes people think that they don't feel realistic at all.
D-Rex certainly has a personality, and several different emotions. As much as I love them, I will agree with IMR: Not the level of emotion Pleo has.
And, as I had said in the chat, they really do run through batteries like a hungry dinosaur.
I hope I've been helpful!