Games on Newgrounds are very underrated, and I can't imagine how long it would take to make a game like this. Puts my work to shame.
Graphics: It's good to see a Mario-based game with actual hand drawn sprites. Doesn't get much better than this in Flash games.
Interactivity: A lot more detailed than I expected, and I didn't experience any slow downs.
Sound: Good sound quality and some nice remixes of original Mario tunes.
Overall: Possibly the best side-scrolling Flash game I've ever played. This definitely deserves front page.