Well, I must say I'm really impressed with this, this is so good.
The header is just great, some might think it's a tad too big but I like it. The only remark I can make on it is that Mario looks a tad sharper than Luigi and his friends. Make those three somewhat sharper maybe so that all four of them look equally sharp. The logotype is very good as well. Might I ask what font that is?
The navigation is good as well, although I prefer the top navigation more. Both are great though, no changes needed on that in my opinion.
As for the rest, I love how you gave your personal touch to everything, I reallly like that. The iconry looks really good and the buttons look good as well.
Overall it's looking very nice, can't wait to see it online, and can't wait to see more of your work.