From what I read, Burch's book is mostly concerned with self-acceptance and identity, and kind of reads like a self-help book fused with his own personal story. Personally, I skipped a lot of the autobio bits, and what's left is kind of 'well, duh!' in terms of telling you to be who you are instead of who society tells you to be. It's okay, but like I said, sort of feels like he's telling his story for his sake and not the readers'.
'There's a Baby in my Bed!', as you would probably guess, is written for an outsider looking in. Also, her views on classification and motivation of AB behaviors differ pretty significantly from my own (and, I imagine, most others here). Her book is targeted to what she calls 'little ones', people for whom regression is a psychological necessity, and for whom sexuality plays a minor or non-existent role. It divides ABs into those that 'have to' and those that 'want to' rather sharply, and leaves the latter largely unexplored.
I, myself, sort of enjoyed these other books more... they're about 'how' than 'why'. In other words, once you've decided that AB/DL is a part of your life and anyone who doesn't like it can take a hike, these would probably be of more practical use.
'The Age Play and Diaper Fetish Handbook' by Penny Barber (aka PamperedPenny) - A pretty good primer for the AB/DL scene overall, has a lot of information on practices and resources and is more specifically tailored to ABDL than to ageplay in general.
'Ageplay: from Diapers to Diplomas' by Paul Rulof - Also pretty good, has a lot more information on things like LB/LG and other non-ABDL bottom roles. Deals a lot with the semantics of roleplay and how to develop, achieve, sustain, and leave little space safely.
'The Toybag Guide to Age Play' by Lee Harrington - Another more general ageplay book, it's pretty short, and I get the feeling that the author isn't specifically in to ageplay as opposed to kinks in general, it discusses other fetishes a fair bit, such as leather, latex, etc. Still a decent resource.