I had the retreat in 2009 thanks to a friend who unfortunately got injured and did not make it. His wife had paid for it for him as a gift and he hated to see it go to waste so told me to take the wristband for it when I got his packet.
Can say there are a couple things I truly enjoyed.
1) far easier to get to a porta potti
2) someplace to sit other than the ground. Was very important to me after the race (it was my first full)
3) gear check much easier
4) there was far more variety of food available before AND after the race. Not just bananas, apples, and the same muffins I swear they've been passing off on us for years.

Before it was fruit, yogurt, eggs (hard boiled if I remember), bagels, toast, etc. After there was fruit salad, pasta, rolls, lunchmeat/cheese, cookies, brownies. Couple other things I just cannot recall at the moment. So unless they've changed it, the food is different than what is given to you after the race outside the tent.
On the flip side, you aren't hanging around with friends before the race. I ran back and forth that year (if it had been 2010 I would've been waving from inside

)