Some of this has probably been stated, I have not read the replies, but here it is anyway.
The two best/worth while are going to be The Unofficial Guide and The Passporter. I think it depends what you want. I feel that the Passporter is for organizing, with information. I think the UG is going to give you an unbiased report of everything. Theyll give you the pros and the cons. They tell like it isthe good, the bad, the ugly. They are in-depth. It will help you plan. It will help you save time. It will help you save money. It does not help you organize. Having the current guidebook gives you access to parts of the website. I buy a new UG every other year as soon as they come out (September-October). They are little out of-date as soon as they come out (Disney is always changing), but updates are on the website.
The Birnbaum book is all pro-Disney and too full of pixie dust to be of much real use. I do think it is great to get the anti-Disney person on board and good for kids.