The art is redrawn, but surprisingly faithful to the original version.
Motion is smooth for the most part.
It really looks and acts like the classic cartridge version. The beauty of this game is that you can run it on almost any PC still alive. Grab that 286 you've been letting the kids use as a gerbil adventure toy and fire it up for some Mario action. This is probably the web's most popular game download, ever. Take 2 minutes and get it.