After getting used to the general structure (Books, Pages, sections), and ignoring most tools, it grew on me.
Which, like the OneNote version in Office on OS X, can only sync to a Microsoft account through OneDrive and can not even create local notebooks.
That may be a show stopper.
Now on OS X it will go into offline mode and save to an ever growing local temporary file, but you can't choose to create a local notebook.
I had to use the full version of 2016 that I could get with Office 365 on my Surface to save to a local directory.
https://support.office.com/en-us/article/Frequently-Asked-Qu...
https://answers.microsoft.com/en-us/insider/forum/insider_wi...
http://arstechnica.com/apple/2014/03/new-free-onenote-for-os...
A good example of what could be a subtle change making a big difference is both creating new note & deleting an existing note happens instantly now, past versions there was some a brief lag. This is part of the reason why even a little bloat can really suck in anything you use multiple times a day.
Since I also use Windows the problem I have is getting to those notes on my Windows 10 boxes. The only fast way I've found is to log into iCloud.com. Not perfect but good enough.