I like it. Normally I hate equation editors because I get horrible eyestrain from anything with little icons and fine mouse work. But this shows me the code, I can paste it into iPython Notebook, and gradually learn the syntax.
If you're trying to learn how to typeset formulae with LaTeX, detexify is great - it lets you draw a symbol, and tries to identify it: http://detexify.kirelabs.org/classify.html
This online editor was a life-safing item previous semester. Absolutely brilliant.
On the online equation editor side I use https://www.latex4technics.com a lot.
Especially the auto-completion saves time and they allow outstanding customizations.
Brilliant tool!
Pretty handy for quickly iterating on things. Especially complicated expressions within matrices (or things like that which quickly turn into a jumbled mess in TeX). I remember using this site a few years ago during graduate school.
Used it a year back for some classwork, and it made life easy.