The SNES sounds so great on paper, but the reality seems pretty lacking.
The CPU is slow as shit, so games of my favorite genre (shooters) are constantly dragging. I enjoy the Thunder Force III SNES port, but it slows down at the drop of a hat. Same with Super R-Type. For me this is a big deal. Mode 7 can kiss my ass-- I'm not sure it was put to good use more than once or twice. Most of the time it was used as a gimmick that slowed down the framerate. The high color count is nice, but really, most games don't look any more colorful than Turbo/PCE games. And I prefer the Turbo's color palette.
The sound is probably the biggest disappointed. While the SNES has a sound chip technically superior to both the Genesis and Turbo, I find most of the music all sounds so generic and same-y. Another forum member put it nicely when he said the SNES's music is kind of in a funny limbo between "real" music and chip music.