As a fan of Earthworm Jim growing up this is an interesting case of nostalgia hitting up with what amounts to a lousy port.
Back in the SNES days Earthworm Jim was considered a fun game due to it's unique charm. Excellent gameplay, responsive controls, outrageous humor, terrific song and music, and fair difficulty. It's everything you want in a game, something that doesn't take itself too seriously and if you screwed up it wasn't the game's fault it's because you weren't good enough.
Some are present here, however the port wasn't a clean one.
Hit detection can be dodgy, missing levels, sounds that just aren't plumb there. Even among the poor ports out there this is probably the worst of the bunch.
If you want to get Earthworm Jim, I'd recommend the SNES/Sega/SegaCD ports. You're missing out by getting this even if you are a fan of Earthworm Jim.