I lean HEAVILY on a sim for my intrument people, both the newbs giving it a first try at the instrument and the veterans looking for an IPC. They both complain heavily at first...the newbies saying "This thing doesn't fly like an airplane!" (to which it shouldn't. That's not it's purpose. It's purpose is to teach you to scan) and the veterans saying "It would have worked if we were up in the plane!" (to which I smile on the inside knowing that the end result would have been exactly the same or worse).
After a half hour or so of figuring out how to get it trimmed and waking up their sleepy scan, they start to really appreciate what it can do, especially the "OK, let's pause it for a second and have a look at your ground track" capability, and towards the end of a 2 hour block, they're saying "Hey, let's do another sim next time before we go up..."
It's my opinion that a simulator without an experienced CFII is like a gun without bullets. Nearly useless. Anyone can set up a basic flight sim to put themselves 20 miles from an airport, intercept the localizer and fly it down to minimums. That's cake. Unfortunately, that's not instrument flying.
A sim NEEDS a capable CFII in order to be effective. The CFII needs to be able to play the part of ATC perfectly. They can't stumble for words, issuing clearances, giving headings and altitudes, traffic calls, "say intentions", etc. The bread and butter of being a good instrument pilot is knowing that the "right now" is already gone, and what's important is what's going to happen or where you're gonna be in the next few minutes. Here are some examples of what a CFII can do that you can't do in a sim alone and really learn anything from it:
1. Vector you to within 2 or 3 miles of a Final Approach Fix on an ILS but keep you 2000 feet above the FAF altitude. Now what?
2. Drop the visibility to less than the prescribed mins so that when you reach DA, you see nothing. Now what?
3. You decide to go missed. You start the climbout and ATC says "Say intentions." Now what?
4. You tell ATC you want to hold at a particular VOR. As you start to tune in the frequency of the VOR, ATC (your CFII) says "XXX VOR is out of service. I can give you the hold at the NDB though..." Now what?
5. In the hold, you tune in the ATIS for a nearby airport and you decide you're going there as a diversion. You call ATC and tell them you want the ILS because the ceiling is already way below the minimums for the non-precision approach, and they come back with "ILS XX glideslope out of service". Now what?
6. ATC calls you back and tells you that the visibility is improving at your original destination airport and they can give you the ILS again if you want it. You say "Yes!", but as you turn to the initial vector ATC issues, you realize it's a coastal airport and the wind is coming in off the water, and the sun is going down. The temperature is dropping and that fog is going to get thicker before it lifts. Just as you finish this thought ATC calls back and says "N12345, tower says the RVR just went below minimums again. I can hold you at the marker if you want..." and you agree. He says "Roger...N12345, you're cleared to the ABCDE intersection via radar vectors. Turn right heading 220, climb and maintain three thousand, expect the ILS 24. Advise when you have information Kilo"
7. It takes 2 or 3 passes of the ATIS before you've got everything you need, and now you dig up the approach plate to check the minimums and brief the approach, but...
Congratulations, you're right back at number 1 again! Now what?
My point in all of this is that for a sim to be effective, you need an instructor who can throw real-world curveballs at you. Imagine if you went to school as a kid and there was no teacher. You showed up, walked into class and saw a message written on the board that read "No teacher. Choose what you want to learn and teach yourself". How far would you get?
It's the responsibility of your instructor to expose you to borderline chaos.
That's what instrument flying is all about. One thousand decision per minute x however many minutes you're flying = real world IFR.
If you're going to choose to sit at home by yourself and try to learn IFR using a computer based flight sim, make sure you're squawking 7600 in your transponder, because that's the level of realism your "ATC" will have for you. There's a reason why you can't log "solo" sim time.
Oh, and I utilize an Elite PI-135 PCATD.
Inst: "So how far out so we make our initial call-up?"
Student: "10 miles"
Inst: "OK, let's make that call"
Student: "Airport Traffic, Cessna 172, 3 miles east..."