Hello, having been around Agile for a while and already a certified scrum master (CSM) I passed the PMI ACP exam in June.
I used the PMPrep Cast ACP product which helped provide an overview of the exam and coveredthe general content on the exam. In conjunction, Mike Griffiths PMI-ACP exam prep book and a third party test bank.
The benefits of using three different products I believe are that each product tends to focus on different exam area content. Each product has content that didn’t appear on the exam. However, the content that was similar to all products was on the exam.
I also watched various U-tube videos of prominent agile authors that have written books that are referenced as sources for the exam. I did not buy all the books; just the ones that I thought could be most beneficial to my Agile practice.
My overall study time was about 3 weeks, a few hours a day; I did about 900 prep test questions, probably overkill. The exam was pretty straight forward, typical PMI exam, a lot of easy questions, some that required some thought or analysis, others that were difficult, had to guess. The biggest takeaway from the exam was that there was a lot more Lean type questions on the exam than I expected, not as many on Scrum. Please keep in mind I purposely took the exam before the update which is to occur later in 2015. In my mind, the exam needs to be updated, but it does give you a good broad overview to a lot Agile concepts and methodologies.
Good luck,