I like the look! So few people attempt black, but you did it well, and it fits with your products/themes.
The first page loaded quickly, so you've done a good job with those graphics. The detail page for each shirt is nicely done; I like the built-in zoom. I would label the front/back views to make it obvious that the shirts are printed on both sides.
I like the page that lists all the shirts, and that you can choose to view them all on one page. Nice and clean (and somewhat like what I wrote for my own site). I always try to convince people to make the first image of the shirt
larger. They are 175 tall now, bump it to 250. You've got the room! And put the backside image right next to it. Now the user can see enough of the shirt to be SOLD on it without having to click on ANYTHING. Whereas if they didn't notice anything interesting to them in a small image of just one side of the shirt, would they really be motivated to click and wait for another page? And repeat that process for how many shirts?
Let your product sell itself by clearly presenting itself from the very first view. Don't hide it behind unnecessary clicks.

Sorry, that is my soapbox. Someone, somewhere once wrote a template with a small view that leads to a somewhat larger view, that leads to a larger view... and I've been moaning about it ever since ;-)
I like it!
And congratulations on going live. I wrote my site last spring, and still have not gone live. Do you print your own shirts? This winter I've been adding some space so I'll have enough room to actually use all the equipment I acquired/built over the past two years. I hope to make it this spring / before summer.