Taxis in the Netherlands are generally great (though expensive), with the notable exception of Amsterdam. There they refuse you service if the trip is not long enough to their liking. They are typically rude, and oftentimes armed. It's fun to go to the taxi-stand at Amsterdam central station and notice the permanent presence of at least two police cars there. They're not there to protect taxi drivers from the population, that's for sure.
I've taken UberPop in Amsterdam and it's great. Unfortunately, the Uber drivers need to ask you to sit in front, to reduce the risk of being attacked by vigilante taxi drivers. It's a breath of fresh air in a thoroughly unpleasant market, and I hope legislation gets passed soon to make it legal.