The best part of spin.js is it's ease of use, and how simple it makes the creation of multiple animations in one page. It also helps with code organization and cleanliness. I like that you are able to create unique spinners for any type of project or app that requires one.
I do not dislike anything about Spin.js, but if there was something that I would like changed, then I'd say make it more clear what all the tools (animation types, spinner types, etc) mean and what they're capable of doingβ¦