I have not been there in a few years but also found the taxis in Warsaw to be honest. I have never been taken for a ride.

When you enter the airport lobby from customs, ignore all the people at the lobby who try to get your business. Go directly to the taxi stand outside.

The hotel taxis are nicer (I think they were Mercedes when I was there) but cost significantly more. By US and European standards, it is still decent though.

Steven