Actually, I had that sim, and it wasn't that great. If you're just an armchair warrior looking for fun then it's fine, but it doesn't have enough realistic simulation to use it for procedures/systems training, etc.
FMS had most but definently not all functions, as did the nav/PDF, etc. But most of the buttons on the overhead panel did nothing.

It's ok maybe to get used to the layout and displays, but it's not a systems trainer.


Now in contrast the newer stuff like the Airbus Deluxe, 737PIC, PMDG 747, etc. have basically 100% real simulation of every little thing and could really be used for practice.

On top of that why waste time with FS2004? Go for FSX!