Flight Sims are great fun and have a huge worldwide following and has been mentioned can be a useful tool to aid in instrument flight practice, but other than that I believe they have little to offer a full time pilot as a number of omissions have had to be made in the construction of the sim to make it ‘flyable for all’.
The one thing that has always bugged me with them is the lack of detail in cockpit procedure manuals an aspect which until late have been totally overlooked, even today’s high end add-on aircraft like PDGM’s 747 series and the mentioned ATR who’s manuals are very concise lack the totality of full scale cockpit procedures through all phases of flight, the FMC provided is only partially operational and can be quirky at times and a lot of the required information for it’s use has to be either guessed or trawled up from various windows in the sim with little to aid in this.
Other than that, try a full flight hands on into the former Kai Tak in some dodgy weather and get it right makes you slightly overlook the short comings of the game.