Overall I'm guessing your going with simplicity. That is a good thing, but... With simple things you have to be precise to make it look good. On your home page make the green writing header even from the top and the left. Otherwise it looks awkward. And after someone uploads something there s no spacing between the site header and the image that was uploaded.

Also, on the homepage, the upload area and the Browse button could be improved. Instead of a default grey button design one for it so it flows with the design and the upload button.

Also as a side-note, it could just be me but your light-box image display is not working.

Matt.

Smart but...