We vote Sci Fi!
We had lunch there a few months ago. It was so cool to get out of the sun and heat of the day (and noisy crowds) and go into a cool, dark, and very quiet "drive-in." Our daughter loved the car that we ate in and thought that the movie trailers and shorts were hilarious.
We had burgers, fries, and a milkshake and all were excellent. I dont know if I would order more complicated items there, but the burgers were great and the milkshake delicious.
It was also a really nice break from touring MGM, too. The restaurant must be the quietest at WDW -- everyone was so intent on listening to their "speakers" that we really felt rested when we left!
We didn't try SciFi on any previous trips because I had read so many bad reviews. Then a friend told me that this is her kids' favorite and how could we miss it? So glad we tried it this time!