It's like an advance, if you were working with a publisher. The difference being that the investors don't recoup this advance; they are doing it specifically to support the author. I like the concept, it helps creators get around the gates put up by publishers and industries to maintain control of a product they don't actually create.
It's not well regulated, so people need to be smart and cautious when deciding where to spend money. Evans actually published the books, so I assume his backers are satisfied. Whether they're comfortable with backing him after finding out what he's really like... I don't know. I assume a few of them wish they could take it back. As Nancy Pelosi would've said, they needed to read the book to know what was in it.