My opinion of the "big three"
I like Birnbaums for first timers. Also for anyone who wants an "easy" trip. Color photos, upbeat descriptions, not overwhelming. Reading Birnbaums is easy and fun and convinces you a Disney trip will be easy and fun.
I like Passporter as a planning guide. I like the pockets and places for notes and the checklists. It has a lot of information in it and I like their rating system - which balances Dave's opinion with Jennifer's with their readers. I like it for repeat visitors and anyone who doesn't think Birnbaums has enough depth, or who wants the planning features.
I don't like the UG (although I like the queuing theory stuff). I think its overwhelming unless you are really going to get into the trip. I don't agree with a lot of the opinions and have a problem anytime opinions are presented as fact (UG insists every small child will return to the hotel room and nap. Hah! Never met mine.) For first timers in particular its a big book without a lot of pictures, a whole lot of detail, and it makes a Disney trip sound like joining the Marines. Had it been my first exposure to WDW, I'd have cancelled the trip and gone to sit on a beach in Mexico. Obviously other people are different (I don't like Boma either, so maybe I'm some sort of mutant freak). It is, however, a great book for someone who really wants depth, and their touring plans are worth the price alone - if you will commando.
As for other resources, TourGuide Mike isn't terribly organized. Some of his content is good, some of it needs work. Allearsnet and wdwinfo are good for a lot of things, but web resources aren't real portable