My wife and I used them from the airport to our hotel in Prague and it was brilliant. The drivers are all English speakers, mostly expats, and they give you lots of information about the city on the way to your hotel as well as bar/restaurant tips and local scams, the price was the same as the airport taxis, about £15.
We arrived at Easter to find all hotels in the central area full so we stayed a little out of the city. One night the taxi driver wanted five times the normal amount of money for the fare. After arguing with him, my husband went into the hotel to get the owner to come out and talk to the driver. When he exited the taxi the taxi driver then drove off at high speed with me in the back and central locked all the doors. After I promised him I would pay the amount he requested he stopped the taxi and let me out. I would not trust any of the taxi drivers there.
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