I finished IFS at the end of June. I had no previous flight experience, no knowledge of how a plane works besides pull the stick back and it goes up (STS). Having said that, if you go into IFS with the mindset that you're going to be a sponge, absorbing all the knowledge that the IP's teach, taking everything for what it is, and not allowing one bad flight to wreck you, you can get through this program.
Saying that, IFS in 4 weeks provided me more of a challenge than 4 yrs of college. I studied harder at IFS than I did in college. Its really your attitude and how you take failure and success that proves your measure as a student. We had guys that went to 88 and 89 rides that "rally backed" from bad flights, the work load and the stress and finished. Then again, we also had guys that didnt and washed out.
Currently I'm 1month away from track selecting. Just shutup and do what the IP's tell you, study hard, and you'll get through it. It sucks, but like everything just push through.