I've been to it about 10 times (10 of the past 12 years - signed up the other years but bailed due to weather). Basically, you will learn whetever you want to learn. If you want to work on teaching skills, or exam prep (skiing or teaching) or personal skiing, or shut up and ski fast, or whatever. Because there are so many people there, there are always enough people to make up groups that want to work on the same thing. I wouldn't go back every year if it wasn't worth it. It's incredibly cheap for what you get out of it. It's an educational event during the day and a party at night (if you want it to be). By far, it's the best event you could ever go to. Think of all the great stuff you've heard about the Epic Ski Academy, then have 500 people show up. All of the clinicians are examiners, and the clinicians for the Master's Academy are the National Alpine Demo Team. They have loads of demo vans there all week. Last year I only skied on my own skis on monday morning and friday afternoon. I've even demo'd helmets. Other people have demo'd boots. Gregg Hoffman and his crew fro Green Mountain Orthodic Labs (GMOL) are there all week to do fittings. You'll also get your group video taped, and get a chance to review the footage with your clinician. The PSIA "company store" will be there to sell you any PSIA literature and videos (they even have some logo clothing for sale).
I've never met anyone who has regretted it (other than the really bad weather years), and most people make a habit of going every year because it's such a great event.