Buried Giant: Characters and action
Axl and Beatrice are clearly the protagonists of the book, although Gawain gets a major section in his own voice. The principal and secondary antagonists (dragon and trolls) don't even appear. One thing I noticed was that the secondary characters and monsters seemed more clearly drawn that the principals, which I thought was somehow related to the fact that existed only in the present, and so the lack of back-story wasn't so important, which in turn has something to do with the magic in the story. At the end of the book I had a clearer picture of the boatman (or men?), the villagers, the monks, in their context, than I did of Axl and Beatrice. Well maybe not the boatmen, but they were vibrant if vague. And I thought the secondary monsters were great as well - the dungeon crawl was actually scary. Good stuff.
However I can't really imagine anyone saying, "Hey! I'd like to play that character!" even if they were NPCs, which is what I think Gaiman was pointing to when he said
The excitements that the book would deliver were this a more formulaic or crowd-pleasing novel are, here, when they appear, not exciting, perhaps because they would be young people's adventures, and this is, at its heart, a book about two [old] people who are now past all adventure
What did people think of the characters? How could it make sense to play being past adventure?