Question for those who have recently used the PMP –– does it still provide you the ability to “skip the line” (even when reservation required), as in for instance the D’Orsay had one line for those wishing to buy tickets upon arrival and those who held the pass or tickets purchased online. Does that still work the same way?
As for deciding if the pass is worth it, when I plan a trip, I map out everything I want to do, see what is on my itinerary that is included with the pass, add up the entrance fees and if the pass is less than the total of the entrance fees, I buy the pass.
If the cost makes sense to your plans, having the pass is nice as well because you can decide on the fly to visit a place you might not have planned to (and perhaps might not want to spend the euro for otherwise).
I have never purchased the pass online, opting instead, once in Paris, to pop into the nearest small (not busy) attraction that sells it.