It's sort of a mix of both Super Mario Bros 3 for NES and Super Mario World for SNES. Much of the art is from SMB3 (frog suit, racoon suit etc...) while many of the sound effects and music is from SMBW. It's great. There is lot's of voice, and this is before Super Mario 64 when they standardized marios sound samples, so it's probably some Gottlieb factory worker using a really insensitive stereotypical italian voice yelling "HOLY MACARONI!" and stuff.
I know lots of people say they don't like this machine because of it's diminished size, but I think it's a blast. I'm way happy with it, and feel it has tons to do (I love the video mode on the dot matrix, my wife finally jumped over the ghost last night). I guess if I had paid full price I would probably feel differently, but as it is, I'm really glad I got this machine (wish I was home playing it right now