I had a similar concern about "okay, is Bren someone I can actually start caring about?", but I kind of think the backstory chapters need to be handled as a separate unit, if only so there can be the disclaimer "don't actually worry about any of these folks" and then the first Bren chapter can start off on a better footing. (And people who've bounced off the books before, or who think they're likely to do so, can start there...)