I could no longer sync between my Android phone and my Windows desktop computer.
A real shame, because other than that it's an excellent choice. I normally prefer Google services, but Google Keep, it's counterpart competitor, it's not nearly as complete in terms of tools/features. For now I'm using WizNote, better than Keep too, not sure I like it better than OneNote yet, but it does sync just fine.
Hopefully Keep will catch up with OneNote soon.