Easy, well documented, extremely powerful
It makes me feel lazy :-D
Sheetsu powered my e-learning application for the last 14 months, I'm a paying user with no affiliations.
I'm no dev.
It is a tool I can't live without (makers please do not read this) ;-)
All my data is in three separate Google Spreadsheet (each of them of course has redundancy, versioning, collaboration tools). Some of this data is sent to two different websites, some is crunched and then sent.
What is unique, to me, is the ability to abstract your numbers, code, elements, and let them be used for different meanings. The same numbers provide html code, statistics, even provide room for feedbacks.
Code is lean, easy to maintain, docs are good, and support is fast!
Handlebars will make my code even cleaner!