I have to admit I didn't find much particularly compelling about the game. It seems very similar to the Teenage Mutant Ninja Turtles II: The Arcade Game, which I'd played through on NES a few years ago but didn't find particularly memorable. TMNT IV has a little more variety in terms of locales and there are some stages that shake thing up a bit, specifically a couple of hoverboard levels, including one that makes good use of the SNES's Mode 7 effects. I'm sure fans of the cartoons would get a lot more out of it (I never saw the appeal myself), but for me this just felt like business as usual, and a pretty mindless experience on the normal difficulty level.
Not much more to say about this. Finishing this game completes the list of most famous TMNT video games, so I don't have to worry too much about spending more time on them. The one other TMNT game that I'm curious about is Teenage Mutant Ninja Turtles: Smash-Up, a Smash Bros. clone that was co-developed by some of the development staff of the Smash Bros. games. I'm not expecting much from it, but I'll probably check it out at some point.