I've used them a few times to print t-shirts for me. Shipping was quick. The quality on some was better than others. They had quite a few limitations with what kind of artwork they could print, but I think they have a digital press option now, and their product line has grown quite a bit since last year at this time.
I think you can also have an unlimited number of products in your store, you can't have a free-unlimited at Cafe Press, but I believe you can at Zazzle.
A very good thing to note about Spreadshirt is that they actually reply to queries, it was almost immediate.