They are VERY real in what you can learn and then apply directly to the field. I learned about everything on the sim and then almost seamlessly transferred it to the real thing.
Here is what I am talking about. Watch this video.
http://www.youtube.com/watch?v=hvHGhjW8CHo

In December of 2004 I was a pretty good hotdogger and an ok pilot. I got the sim and within 4 months I had learned to fly at this level. Not that its earth shattering skill, but all of the skills I learned on AFPD I can now re create in real life.