flying_saucepan,
what FougaMagister says is incorrect I'm afraid. An FNPT II sim is not "as realistic as it gets". This is why it's an FNPT II !!
The visuals and motion are much simpler than a full up-to-date airline sim, therefore giving less realism.
The main difference though will be in handling - the FNPT II is not required to have anywhere near the fidelity of a full sim in terms of handling. This can result in some strange handling characteristics which will be very much less than realistic.
I don't mean this in any way as a criticism of any FTO's product, simply to point out the differences between a flight training device and a full sim. The FNPT II is an excellent training tool when used for the correct purpose, but it's important for you as the customer to understand what it is and what it isn't.