I just went through the process of adding a pattern, and found it frustrating and tedious. I couldn't save partial information before switching tabs, and it repeatedly deleted what I had entered. I suspect these are the normal sort of defects that need to get shaken out of any new site, and I would be happy to help with repro cases if that would be of use.
Mostly, there should be some indication of what size photo is allowed. I wasn't able to upload the large photos (~5M) that I use for my pattern, which was frustrating. There was a tiny little "Error" message that appeared in the upper right, but gave me no context.
On a whim I reduced my beauty pic to a few K, and it uploaded just fine. So I'm assuming there is a size limit, and I was exceeding it.
I look forward to using the site!