I wonder how many of you guys proclaiming that "Flight Sim is the work of the Devil" have actually seen the latest version.
IMHO the two unavoidable drawbacks of the typical PC sim are:
1) There is a small screen in front of you, so you completely lack the side view. To "fit more in" you have to destroy the perspective. (See point 2).
I know you can strap things to your head and "look to one side" and the screen view follows, but you still lack the peripheral vision.
2) It is extremely hard to reconcile the distance from your eye to the PC screen with the real distance from your eye to e.g. the real compass on the real coaming, so it is very hard to judge visual angles in a sim.
So for circuits and landings I would say that sims are worse than useless.
But they are fine for other stuff (as others have said many times before me):
1) If you have the scenery, then you can practice nav routes.
2) You can practice instrument nav and procedures in extreme winds, etc.