I've seen a little of PPS, but unless the bloke showing me was doing it wrong, was surprised by the lack of route optimisation. By that I mean PPS can get you from A to B by the shortest airways route, but as far as I could see, paid no attention to the weather - unlike Jeppesen. So I suppose you need to decide between burning extra fuel because of an apparent lack of optimisation, or paying for a Jeppesen product to do that, which will cost you more.
For me, the jury is still out,and I'd be interested to hear more of the benefits of PPS - can it optimise? - if someone has the inclination.