I just discovered this feature so I haven't played with it enough yet but it seems to tick all my boxes. One thing that I found confusing about the UX though was that I didn't realize at first I could continue searching around and adding content, so when I added my first bit of content and clicked "Create Notebook" and then subsequently navigated somewhere else and wanted to add content I ended up creating another notebook instead of adding it to a pre-existing one. Or sometimes I come back and want to add more content to an existing notebook, but I don't see how to do that.