It would be much better executed for the public preview testing of this feature if:
1. It was not hidden inside the Shared - Photos tab, which is not the default location when going into Shared section. I would have thought a Memory tab next to Albums in the Photos section would be more sensible.
2. It can be accessed quickly through the Photos section under Gallery - For You, maybe replacing that useless and confusing Access your memories tile with the Create your memories tile.
3. It can be extended to posting text only without photos. This could be adding journaling functions into M365/OneDrive platform, something Apple is already about to release the native app for. Microsoft can also look into other great services like DayOne, FamilyAlbum, Tinybeans, Backthen, etc.
4. I'm sure it's not difficult to have rich text editor for the post.
5. When creating post, the photos selection interface needs to be more efficient with search function (name, word, tag, date, location, etc.) and sorting.
6. The story post doesn't support tag for easy categorisation and searching.
7. I'm sure some extra flexibility on privacy control would be very attractive to the users, like if the post's sharing permission can be set differently or if we can have multiple story lines shared with different group of people.
8. Microsoft can even make it easier for the OneDrive users to create the posts by directly utilising AI generated/grouped photo/video memory or highlights.