I just installed the Tablet version on my Motorola Xoom (already had Slingplayer for Phones), and I can tell you the picture quality is much more impressive. Also, the new integrated Guide functionality is offers a much easier way to scan what's currently on and change channels.
HOWEVER, the remote functionality for the tablet version is very limited as compared to the Slingplayer for Phones. I can't change discs on my multi-disc player, and I can't bring up recorded shows on the DVR. I have to open the Slingplayer for Phones to select a DVD or a show from the DVR list, and then close it and open the Slingplayer for Tablets. Very annoying. I posted on another category in this forum if you want to see my write-up.