I would totally agree with Jenny based on my experience in using Head First PMP for my PMP preparation. If you serious about getting PMP certification, you need to read PMBOK guide multiple times and understand the concepts. But the PMBOK guide like any other reference books contains theory which could make us fall asleep or lose interest. Reading HF PMP first makes the task of reading PMBOK guide much easier.
I am a fan of HF series, which is why I checked out HF PMP book. And I must say, the authors did not disappoint me. HF series still rules.