I didn't attend any of their courses but did my ATPLS Navs and Techs with their correspondence course. I found them by far the best for me when compared with other ones I have seen. Rather than the 'monkey see, monkey do' or 'learn all the answers to all the questions' approach of some organisations, PPSC tries to teach you to understand the subject. OK so this means a bit more work, but it equips you far better than going into an exam hoping you will get questions you recognise. Of course it may not be to everyone's taste, but it worked for me. They do tend to take you beyond what you need to know to pass the exam, but that allows for you to have a brain fart on the day and still stand a good chance of passing.
By the way, I don't work for or have any connection with PPSC!
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"Take-off is optional, Landing is mandatory"