A few thoughts on my experience so far preparing for the PMP exam:
1. There are apparently two types of people who fail the PMP exam: a) the experienced project managers who have trouble ignoring what they do in real life and accepting the PMBOK way as the way it should be done; b) the wannabe project managers who may have a significant amount of book knowledge but haven't had many opportunities to apply that knowledge in real world large scale projects. I belong to the second category, with a slight advantage due to the fact that while I don't manage large projects requiring sophisticated PM approaches, I have, for the past four years, been very close to large, complex projects using advance project management methods. My strategy for mitigating my weakness (lack of direct experience managing large projects) is to connect concepts to real life projects I know of, and to try to answer as many of the more difficult, situational questions I can find.
2. Some things I read about or heard about turned out to be true: a) You can't rely on PMBOK alone; b) Rita Mulcahy's PMP Exam Prep is excellent; c) You can't rely on memorization -- I certainly can't because I can barely memorize my own telephone number, but you have to memorize key formulas and the processes matrix. Even with the formulas, it's best to understand what they mean to have a chance of reconstructing them should memory fail.
3. Iteration is key: Don't expect to absorb everything in any of the knowledge areas with one pass. Read the material, take some sample test questions, see what you're missing, move on to another topic, then come back to revisit key concepts and get a deeper understanding.
4. I am having a very difficult time with inputs and outputs. I'm less than a month away from the exam and I'm estimating that I know 50% of them. I know the obvious, logical ones.
5. I never thought I would have to learn network diagrams, forward and backward passes, but it's not that hard. I'll get it wrong if they throw a trick question at me but I can get the basic critical path and float questions.
That's it for now. More to come when I pass/fail at the end of the month.