My DF and I LOVED Sci-Fi! The atmosphere is great, yes, very cool restaurant, very quiet with all the kids glued to the screen, cute decor and some of the friendliest service we've ever had.
I had the burger, and it was by far the best hamburger I've had on Disney. of course, the only burgers I've had in Disney were at various CS places, and one at Whispering Canyon Cafe which was so dry it was inedible. But the burger in sci-fi had great flavor and was extremely filling. We loved our desserts, too!
It's not an economical use of a TS credit if you're on the dining plan instead of using that credit for, say, Le Cellier, but out of pocket we found it to be a pretty good deal.
It's nice to have a TS in DHS we like, since Mama Melrose and 50's PTC were both bad experiences for us.