I got my PMP for reasons #2 (75%) and #3 (25%). So I like badges, what's to to ya :)
My opinion on the Rita Mulcahy material is to stay away from it. I found the presentation to be overblown, self-congratulatory and filled with material that wasn't relevant to the test. Never trust anyone who calls their own work "ground-breaking" or "revolutionary". I could go on for a quite a few paragraphs about my many and varied beefs with Rita's company, but who has that kind of time?
Personally, I highly recommend the Head First PMP book. I had a bias from my university days of only taking seriously books with dense type and long titles. This book put my off of that completely. I started this book two weeks before the exam, did a couple of chapters every day, one from the PMBOK and one from Head First, then took the test.
As for the worth of the certification itself, that remains to be seen. PMI is a decent organization, but if anyone actually did all of the things that they specify for a job, I'm not sure that the job would be completed. I think PMI is in NP, but I don't have the proof handy. To date, the main value has been to expand my mutual points of reference with other business units.