I bought from them last summer with the buy 4 days, get 3 free offer. I had no problem using the tickets 2 weeks ago. That being said, they did shut down right after I bought my tickets and that made me a little nervous in the event of an issue, but I worried for nothing.
Editing to Add: Yes, they did shut down shortly after launching their website last year. But they are up and running now. I have no idea how long the shut down lasted. Once I had successfully uploaded them into
MDE, I didn't pay too much attention.