I found FS really helpful for basic PPL training like general handling, trimming the aircraft, circuts, VOR tracking and basic navigation. I think it would have taken me longer to pass had it not been for practice with Flight Sim. I'll say the same as everyone else here, the weather is un-realistic. Air movement behaves differently in real life, wind gusts aren't modelled properly in FS. The major dis-advantage of FS is where 'feel' is concerned. You can't get a 'feel' for the aircraft, you can't feel the turbulence, the roll, yaw and G forces, plus you don't have the preheral (sp) vision in flight sim that you have in real life. In reality you just have to look outside at the horizon to fly straight and level and know what the aircraft is doing, you can tell by the rush of wind wheather you're going fast or slow. In FS you have to look at the instruments.
All in all it's a good bit of kit for 60 quid and the flight dynamics of the GA aircraft are fairly real, if a little too sensitive in pitch. I know this is a bit of a thread drift, I apologise, I just though I'd stick in my 2 penneth worth on aircraft feel in FS compared to reality.