I like the navigation to the left.
I do have some suggestions:

When i add a product to cart a very small popup will display with the text ‘quantity is updated’ . I would suggest to change the text in 'your product is added to cart. In category view (dog/dog-food) i can’t add a product directly to cart http://d.pr/i/7PWefS (it looks like it is not available) .in productview i can add product to cart http://d.pr/i/gNtpMc (so it is on stock) there is an inconsistancy in the category view. Sometime the button ‘add to cart’ is displayed and sometime not (although the products are in stock
Hope this helps