An ILS in the sim with zero wind, shear and turbulence is a far different beast than one in the air with all of the preceeding.
Learning in the sim to get the idea may save expensive time in the air. A sim that can mix up the weather comes considerably closer to the real world. Add background noise and ATC amending the go around procedure on a poor radio to add to the fun.
The first time flying an ILS in the air, try it without the hood to get a feel for what it is required. One way to do that is to dial up the ILS whenever it is available on the runway you are using.