Ultra Twister is an interesting ride. Back when it was at Great Adventure in the mid 80s, it's lift was straight up, and the first drop was straight down. When it was moved, the lift was modified. It is no longer straight up. The ride is short, but kinda fun. The heartline rolls are fun, but it's no mind blowing roller coaster, and I can see why it never caught on. Like you mentioned, one of the best things it had going for it was the small footprint.
Ultra Twister is not the only one ever built, just the only one in America. I can think of several in Japan. When I'm in Japan this spring I'll try to get some pictures of some.
I know many of us are very fond of Superman: Ultimate Escape. I think we can thank Ultra Twister for the creation of S:UE. The first version Intamin built is Linear Gale at the Tokyo Dome in downtown Tokyo. They had an Ultra Twister, and wanted to replace it with another ride. All they had was this tiny strip of land. It was all built built up around the tiny strip of land, and the "Impulse Coaster" we all know and love was cooked up by Intamin. I wonder if Intamin would have thought of the impulse coaster were it not for the space constraints at Tokyo Dome.
-Peabody