Yep, it's a sewing mat! The mixed results are because (1) parts of the pattern weren't written particularly well and (2) admittedly, I got a little lazy in parts because it's just a sewing mat that I'll only use a couple of times a year on quilt retreats anyway. Nothing I felt like making a masterpiece. As I've said before, "Done is better than perfect," at least in projects such as this. (The nice thing about taking a smallish picture and making it even lower resolution to post on a blog? You can't see the problems!)
Maybe the pattern was written just fine, if you had all the bits of knowledge it assumed you had. One or two bits, I was able to quickly pull out a reference and figure it out. Other bits, I just muddled along as best I could. And I did the binding all by machine again, with the same results as last time. So I still haven't gotten that little technique down. Oh well.
It's functional, and it used up 2 1/4 yards of fabric from my stash, and a bit of scrap batting to boot. And it's done. So it's all good.