I took the Passing Zone. I bought and paid for it. Was it worth it? IMO no. I don't feel like I got $200 or whatever it cost value out of it. But, I went in to it with very low expectations, and they were indeed met. I really did it because it was 'something' available in August - I wanted to start studying, and the Testmasters course didn't start until September. I started in June. I was cranking problems in July. Late July, Passing Zone "started". It's really just a self schedule for study. Divide up the Camara manual in to weeks of study, and there you go... same exact thing. A few "problems of the week" (ranging from 2-8 problems per "week"). Some of them were applicable, many were not.
There were a number of questions that gave me a "WTF?" feeling. I didn't bother asking in the forums though. It may be slightly beneficial as a supplement to the Camara book, but I don't think it's $200+ beneficial.
I also paid $1650 or so for the Testmasters course in Houston. Worth it? I think so. Then again, I am in Texas, and I stayed with my sister (she lives about 6 miles from the hotel where the course was), so I had minimal travel and no lodging expenses. The Testmasters material was quite relevant, but even more important was the classroom discussion. Classroom discussion made the wheels in my head turn and got me curious about certain topics, and made me force myself to understand things that were a bit fuzzy. Without Testmasters, I doubt I would have done nearly as well on the NEC stuff. The instructor for Testmasters for NEC knows his stuff. A lot of example problems I saw elsewhere... aren't quite correct. They also worked out good problems with Engineering Economics, and I think I got all of those on the exam, thanks again to Testmasters.
I also bought the Chelapati manual from Irvine Institute. It was good, but not really styled towards the current PE exam. I found it useful, yes, but the problems go much deeper than what I saw on the exam. The problems on the exam are not deep. More than 5 lines of calculation and you've done the problem wrong. Rapid fire.
I worked through the NCEES practice exam at least 7 times, including the night before the exam. The night before the exam, I completed the entire practice exam in under 2 hours, using only my formula sheet as a reference. I got 79/80 correct (oops). Yes, some were memorized answers, but I worked out every problem in writing as required, had every formula down pat, and knew where everything in my formula sheet workbook was.
Scored a 93 on the real thing.
I spared no expense on this exam, and threw hundreds of hours at studying for it. I finished the morning session in 2 hours, afternoon in 2 1/2. In conclusion, I'll repeat, I wasn't overly impressed with PPI's Passing Zone, and in retrospect, would not do it again. The money would be better spent on the Kaplan sample exam and finding all its flaws (shudder, then laughing maniacally).
