There are two default helicopter flight models within Microsoft Flight Simulator. Both of them are sophisticated and are generally realistic to helicopter flight. As with most simulators, even very expensive ones, there are narrow areas of the flight model that are not represented fully.
Keep in mind...Upon installing Microsoft Flight Simulator, X-Plane, or any other flight simulation software you will be seeing only the basic capabilities of the helicopter simulation flight model. It will be impossible for you to judge the software's true capabilities until you gain some experience on how to configure and use it properly for your specific use.
The flight model you will be using for your PC-based helicopter flight simulator is more than capable of providing a realistic helicopter flight experience. Especially if you intend to fly within the documented flight envelop for your particular aircraft. The helicopter flight model for Microsoft Flight Simulator was developed by a competent group of engineers and programmers, some having extensive experience in the field of helicopter aerodynamics. Some of the same people that have developed the helicopter flight model in Microsoft Flight Simulator have helped develop helicopter flight models for simulators costing hundreds of thousands of dollars.
Helicopter Flight Training Devices that use Microsoft Flight Simulator have been approved for use by both the FAA and JAA for various aspects of helicopter flight training. It is important to understand that these authorities do not certify software individually, that is to say that they do not blanketly certify Microsoft Flight Simulator for training. Instead, these authorities certify particular Flight Training Devices, some of which, happen to use Microsoft Flight Simulator as their software foundation. These Helicopter Flight Training Devices have to demonstrate some degree of flight model accuracy in order to be considered applicable to helicopter flight training. Most flight training devices to not need to simulate the entire flight envelope to meet these requirements.
We have collected feedback from hundreds of our members, many of which are helicopter professionals with extensive experience in the cockpit of light piston and turbine helicopters. The concensus is that Microsoft Flight Simulator provides a helicopter flight model that is adequate for a wide range of realistic flight tasks. Some better than others, but in general, realistic enough to be very useful.