Its got good and bad points...

Good.
Nice introduction to instrument flying, i have practiced a few instrument and ILS appraches locally in the 'SIM', good for learning how to intercept radials etc.. But its no patch for doing the real thing in bumpy conditions with real controllers.
In my PPL i practiced the Timing of the circuit... carb heat 1500 flaps 10 etc.. it slowed the circuit down for me and was cheaper thatn doing endless real ones.
Also nice when practice from xcountry regarding airspace boundaries requiring level changes etc.

BAD
The radio is not realistic and there are no last miniute chnages, holds etc. for NZ its all wrong unmanned towers when there is FIS etc.
Realistic flying... its rubbish the flare and touch down can't be replicated. you can do things that would break the real thing.
Crosswinds are not realistic

if you are in the us find a flight school with a Redbird sim FMX take a look at the web site it is great redbird flight simulations

Redbird use FSX or the commercial licensed version of it, ESP. There's also another variant of ESP developed by Lockheed Martin called Prepar3d which they use for simulators - you can download it and have a play, but they want a monthly fee if you want to keep using it, for what is pretty much just FSX (although it does boast better stability and frame rates).

You can fly the aircraft upside down in FSX without the engine(s) quitting. Great for aeros in the C172 or B737..:p