I remember that Genesis commercial. It's funny, 'cuz I also remember going to a thing back then called the Sega Play Tour. It was at my local mall, they had a bunch of Genesises (Genesii?) set up displaying various games, with Sonic as the marquee display. Next to the main Sonic set up, though, they had a SNES with Mario World, to show the differences I guess, just like that commercial.
The SNES had a line so long that I didn't even bother trying, even though I desperately wanted to play it. I played the Sonic demo over and over, there was pretty much no line for it. It totally backfired on Sega.