No experience but I warmed to them many years ago (late 80's) after reading about them in a French dog magazine. Unfortunately the ones in the photos had cropped ears and docked tails, so I originally thought they looked somewhat different, but I still would like to meet one, one day. I've been told by someone who has met & worked with a couple (as a trainer) that they are very full-on and some have less than ideal temperaments, but I'm hoping that's something which will be worked on if it hasn't been already.
There's a lady with a rescue Pyr who goes to training. As he's a rescue I've no idea what happened to him but he is very very DA and reactive. I'm sure it's not true of all the breed but he's certainly not an easy dog!
Proper workers imo. Great if you can handle them but when bored/under used will direct their drive onto the nearest available item (e;g dogs). Very pretty in their natural state btw. Adam