I have seen them before, and they're kind of cool. It's basically a ready-to-race set that you don't have to assemble. They also made another one that was "Spider-Man vs. The Fly" which I believe was the same layout with different graphics and different cars. The cars didn't ONLY come in these sets; they were all available in blisterpacks also.
i had that set as a kid. I remember very little about it. I think it was battery-operated, I know the cars had what looked like a two-piece G+ chassis with a steerable front wheel section, I know the bodies had elongated front wheel wells to compensate (I think I still have a very battered Cuda funny car), and I know I destroyed mine running Matchbox cars around it.