I spent a week in Paris last month, and while I'd normally ignore an UberPop level, my hotel was down a straight road to the place I was going every day that week, and with UberPop I exactly hit the minimum (€4), whereas paying more than double that I felt guilty enough to walk the 10-15min..
I don't think I've ever had such consistently bad experiences with any taxi service, be it modern or old, global or local. All the UberPop drivers had no GPS, or GPS that didn't work. All had trouble finding me to collect, despite Uber's seemingly straight-forward system. I had to give directions (not just "my hotel's round the next corner", but directions for full longer journeys), luckily my French is just good enough...
After a few trips I stopped trying to save money and went back to UberX and UberBerline. All sorted after that (a couple of language-caused issues, but that's my fault for being English in Paris and not speaking French as well as I'd like!)