Overall I've been really pleased with the yoga mat's performance. I have been using it sporadically at home the last several months and brought it to my yoga weekend for a good workout.
I had already made modifications to the grippy sections (by adding on those triangle sections above the chevron) after a week or two. The center tends to stretch because the block bias runs top to bottom. It would have been better with a different pattern and likely a solid, unpieced back. It creeps about on the rug a bit. That's fine at home, but I was afraid it would really slide on the hardwood/linoleum floors at Kripalu.
While I was there I placed my mat over one of their yoga mats, which stayed put really well. On the one hand, that kind of defeats the purpose of making my own mat. However, it made me happy to take my classes on such a colorful mat (and I dislike the way their mats smell).