The map looks really nice, though I'd say a nice high quality, easily accessible one should be part of every e-book if the paper version has one.
The hyperlinked Character Glossary is probably nice too, considering how many recurring characters there are in TSOIAF. But I have to admit that I don't see any reason not to include that in the normal e-books, besides wanting to sell a higher priced "special edition" of course
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The audio snippets seemed completely pointless to me.
Offering the complete audiobook with the novel to read along I could see as being interesting but that just felt interruptive without adding anything.