I think I like it a lot! I didn't use any interfacing because I was lazy, but the cards inside and the double layering make it sturdy enough for my liking. I'll be writing this pattern up as a free sewing pattern sometime in the next few weeks.
My friend Rachel had a birthday last week, so I sewed one up for her also and put it in the mail before I left town. She hasn't gotten it yet due to mail forwarding issues, but I hope she likes it. Happy Birthday, Rachel!