Hmmm, I've read some of the other posts about how much they like your anatomy, but I simply cannot agree with them. I can imagine how Peach's 3-part spine is your style, but Luigi isn't twice as tall as Mario. He is the taller of the Bros, sure, but he's not skeletally thin. Quite frankly, if you flipped the L on his hat , and gave him a hook-shaped moustache, he'd be a dead ringer for Waluigi.
On a more positive note, I do like the color. The action up front is nice and bright, while it has a soft, serene quality to the background and Peach. How did you do that? Was it hard to get the coloring right?