While I agree about the "staring out of a window" effect, I would never go as far as calling it "Nothing like the real thing", but there is no doubt that it is not a substitute for actual stick time.

Bearing in mind RCKen's list of what it does and doesn't do, the sim can HELP learn techniques and moves.

You can attempt something you've never done in real life, e.g. a Torque Roll or Harrier, practice it ad-nauseum on the sim, and do it on your first tries at the airfield.

The fact that this is doable, points to a good degree of fidelity, albeit with the already stated limitations.

Having a set of 3D glasses and 3D compliant monitor reduces the "staring out of a window" effect.

You're still staring out of that window, but the plane on the other side flies quite realistically given that limitation.