The first FAA-approved simulator, in Paris, France
For IFR training, the simulator (BATD) is second to none. It's possible to repeat an exercise without external pressure and at a very affordable cost. The real flights which were prepared with the simulator are 10 times more efficient: the whole flight can be conducted from the startup clearance at the apron, with all phases of the flight, a lot of aircraft, all weather. It's also a good opportunity to train English and French communication.
GNSS (GPS, RNAV) approaches
The simulator has LNAV and LPV capability.
More details relative to the GPS approaches here.
Before flying IFR to the Isle of Man, Madrid or Copenhague for the first time, it could be usefull to try the approaches to be more confident. With its world wide airport database, the simulator will be of a great help.
Some airfields like Raron or Saanen in Switzerland have very special VFR traffic patterns. Have a look to this special patterns before the day of the real flight.
The simulator is also a valuable (and cheap) tool to improve the skills of the VFR pilot entered inadvertently in IMC.
Simulator and logbook
The simulator training provided by a certified instructor is logged as 'Instrument flight' in the pilot's logbook (14 CFR §61.51).
For IFR students, up to 10 hours of this simulator can replace 10 hours in real flight (14 CFR §61.65).
Low cost and safety factor
The BATD sessions give a higher level of safety, self-confidence and better anticipation: it's possible to create all kinds of failures to react appropriately.
In addition, logging hours of simulator is much cheaper than flying a Cessna 152!
Working days or week-end, even in the evening, whichever the time choosen, you will get good or bad weather, snow, wind shear, day or night, perhaps sun rise, perhaps bird hazard!...