Even with just 2 users, the sync experience is variable and nowhere near as consistent with Google Docs. Sometimes the notebook has to be manually synced, other times it works automatically. With more active users in a class notebook the problem is worse.

To reduce the overhead of a class notebook constantly syncing there could be an option to set how often the teacher would like all users and clients to sync. For example, if the teacher is just sending out a page with instructions for pupils to refer to then the sync frequency can be reduced to a default (e.g. 1 min) but if the teacher is wanting real-time collaboration then they can set it to constantly sync.

You have this great feature to 'Review Student Work' which makes work easy to find but you don't have any tools to mark that work easily or signify to the students that they should look at it. I would like some sort of commenting tool that can be colour coded for different types of comments; I would like a quick click tick and cross and I would like a drag and drop make your own comment bank. It would also be great to have a one click button to send the work back to your own folder so you have your own copy. Thanks!

By transparency i mean the following:
-- It should be obvious to users where their Notebooks are stored, bei either showing the exact URL of the storagelocation or even better show the Name of the Location as (OneDrive for B. xy , OneDrive xy or SharePoint Site xy
-- When opening an existing Notebook, the available storage Locations should be showed to the user as: OneDrive xy, OneDrive f. B. xy, SharePoint Site xy an maybe "Shared by others". Right now it only shows "recent Notebooks" and "open more from OneDrive" as options

It should just be clear to the users, where their Notebooks are stored and from where they can open it.

By simplicity i mean the following:
-- It should be possible to migrate/change the storage Location of existing Notebooks by choosing a new location whithout even having to leave OneNote.
-- Also it should be possible to delete a whole Notebook entirely from whithin OneNote not just closing it, and having to clean it up separately.
-- When Notebooks are deleted from within OneNote or the underlying storageservice (OneDrive etc.) OneNote should remove it immediatly from the list of "Resent Notebooks".

Right now its difficult to explain the concept of OneNote to new users, because it is not transparent where their Notebooks are stored and also where they can find their Team Notebooks just from within OneNote.

Thanks for doing something about this!

This suggestion is to unify a few other suggestions. I realize that OneNote has made a lot of progress in terms of embedding content but a lot of helpful content is excluded because OneNote does not allow iframe embedding.
This feature is partially possible by using Sway as a wrapper but it gives mixed results. E.g. an iframe inside a Sway on a OneNote page will open separately in a browser when using OneNote for Windows 10, but will open on the OneNote page when using OneNote Online.
It would be very useful if one could do that directly in OneNote instead of using Sway as a wrapper and if it would open content on the OneNote page - not a separate browser.