I have bought a lot of Disney travel books, and have read pretty much everything out there.
I personally swear by the PassPorter books. They have lots of information that is well laid out and easy to read. Great maps, a detailed description for most everything, and lot of tips and tricks in one place. It's the one book where I can find pretty much any bit of info I need in one book.
I started collecting Disney travel books with the Birnbaum's guides and I have them all from '89 to about '99.
The Birnbaum's books are too sanitized now to be of any real help. It's been a long time since they actually wrote an opinion about anything. It's essentially a 200 page version of the park map you get at the gate of the park.
The Unofficial Guides are poorly organized in my opinion, and have so much unnecessary "filler" information they're hard to read. They print tons and tons of reader's comments that usually differ in opinion so much that you're right back where you started not knowing if you'd like something or not.
The Disney World for Couples books are also well thought out, and were my favorite before the Passporter books. The biggest drawback is I haven't seen an updated edition for a couple years, so the newest one you may find is still probably a bit out of date.
Frommer's publishes some of the best and most consistant travel books I've ever seen but their WDW book REALLY missed the mark for me. Their coverage of the parks is pretty solid, but the secondary information is arranged a little strangely.
For example many sections are grouped geographically, not WDW-specific, so many times shops and restaurants surrounding WDW are grouped in with those IN WDW, which can be a little confusing.
The biggest letdown is the restaurant coverage. They pretty much beat you over the head in almost EVERY restaurant review that the food in WDW is expensive and lacking in food quality compared to another restaurant elsewhere. I don't think it's realistic for someone to read that and say "hey instead of eating here at EPCOT, let's all hop in the car and drive into Orlando, 'cause I read about this French restaurant that's supposed to be better than the one here..."
Hope this helps, and have a great vacation!