I like the site, what software did you use to design it. Overall it is clean and straight forward.
I do have a couple of suggestions.
1. Customers like to be able to see the design, so when they click on the shirt it would be nice if the design, not just an enlarged copy of the first photo pops up.
2. When I click on the first photo and the second photo pops open a portion of the photo and design is obscured by the PayPal window. If should be moved off the photo.
But over all a very nice site.