From the first time I saw this app on the app store I liked the interface and started using it.
There were some sporadic problems with the program at some points associated with me updating to a new iOS and Mac OS, but since then, they have been fixed and the program now runs smoothly and I have not had a repeat of those problems.
There are other features I would like to see in the next upgrades, however, the way it is, I have to say that this is one of the strongest note taking apps I have used.
I no longer use OneNote, but I now use Outline entirely and sync it across my desktop system only to several drives for secure backups of all my data.
I did have problems with OneDrive and uploading large file sizes, so I had to divide my school files between my hardrive and OneDrive, but since Outline allows me to keep all my data together, I opted for not using OneDrive for syncing files. I do it all on my desktop with multiple redundant drives.
My interaction with Outline support has been excellent. They are eager to respond to my problems, or questions, and are prompt to do respond to my emails.
I can only say that as of now this is a great app.