This seems about as good as can be expected for shuttering a digital store. There have been plenty of others that have not closed with such generous terms (any Plays For Sure™ store, Nintendo Virtual Console, etc.).

For years I've thought that there needs to be precedent for the right of first sale extending to digital purchases, which would help in these situations. As a licensee of a digital work, format shifting should be supported whenever a DRM'd marketplace like this needs to close. Consumers should be provided decryption keys as necessary when a company terminates required DRM servers. Perhaps they can be held in escrow and publicly released for some pre-determined period that overlaps with the final days of the service.

I'm glad these customers have been "made whole" (minus inflation), but it's really not Microsoft's place to be able to claw back an item a person has in their possession. It doesn't apply to physical books, why should it apply just because the medium has changed?