I went to the Sci-Fi when I was about 15ish. It's fantastic. The food isn't spectacular compared to some other high-quality Disney locales, but is still comparable to or better than most of what you'd find in the real world.
The drive-in atmosphere is not to be missed. The trailers are hilarious. They make the whole meal go a lot quicker so even if the service that night is a bit slow you'd never notice.
I'm trying to recall if there was a "Manos:The Hands of Fate" trailer. That's a B (C, D, E, F?)-movie classic. My wife and I are going there in September and I'm looking forward to seeing trailers to movies that I've watched on Mystery Science Theater 3k DVDs since my last meal there.
In other words, MST3k fans or geeks in general will adore this place.