I haven't bought from them yet, but yesterday I received some images from my mum who had just received her package. That atleast looked pretty good!
As a seller, you have a lot of options to work with. You can pick what products to put your design on and how to arrange it on ever product group. You can also set your own pricing margin, which is normally set to 20%. You don't earn a lot, but they do all the work for you after you upload your design, so I really like that. I haven't had much experience with other such services, so I can't really compare on the price department.
Yeah it sounds really cool to be fair, an easy way to get started and earn a little extra if you've got some designs you want to get out there.
Well good luck, I hope you sell a few :)