Do pilots need special training to land Lockheed U-2 reconnaissance aircraft?
All military pilots will receive special training when learning to fly a new aircraft, whether that is in a simulator, a 2 seater version of the same aircraft, or both. An F-16 pilot is not going to fly a F-15 without considerable training. Training is recommended even for light aircraft as well when learning a new model. 

If you are asking whether the U2 is harder to land than many other airplanes then yes, the U2 is a very challenging aircraft to land because of it's shape, but also because the pilot can see very little of the runway. In fact the procedure for landing a U2 calls for a vehicle to speed down the runway behind it with another U2 pilot in it to talk the flying pilot down.