Real pilots were awful when you put them down in front of the PC to fly the simulator
I agree with that, even with FS2004 which is very realistic in places I cant do turns without the AI and VSI because i usually end up descending at an alarming rate, used to do it in reality as well but i'm over that now.
I've also never succeeded in landing a cessna 172 slowly on FS, slowest approach i can handle is 80kts, with moderate flap, anything else just looks wrong. rounding out over the numbers results in floating for a few 100m and then always followed by a bounce. this may be due to microsofts flight model though because i recently got a C152 add on and I can land that quite nicely (approach of about 55-65, touch down at stall).
In my opinion FS is very useful for discovering what things do (controls, instruments, etc..) but not much use for actually doing things.