I saw the mug cozy on Reddit first, and it was so cute I had to learn how to make it. I taught myself how to do crocodile stitch using this site.
The construction of the stitch is really cool because it gives it amazing texture; however, the stitch is very inefficient. It takes two rows to make one row, so to speak. You have to make the foundation "ladder" before you can make the "scales." That, combined with the fact that each scale is made up of ten double crochets, means that it uses A LOT of yarn.
As for the project itself, I think if I were to make it again, I would use a smaller hook so that I could have more scales in a smaller section.
TL;DR I learned crocodile stitch and it's really cool and I'm super happy with the way my mug cozy came out as a result!