We went last year. It's not at all formal but it is EXTREMELY crowded. First, get there at least 30 minutes before you were planning to because there is terrible traffic once you get to Route 1. Hopefully they won't have the stupid cigar area like they did last year because it made walking around outside very unpleasant (but I am sure they will). It's very difficult to find places because the directly they give out is useless. On the bright side, some of the stuff they served was very good. The crowd was younger and hipper than my wife and me. I didn't care, I was there for the food.
It's available for $60 today at Westchester Magazine's Deal of the Day. Last year I paid $37.50 and would buy it again for that price but not $60 (and certainly not regular price of $75). They sold VIP badges for $100 that let you get in early and probably make the whole thing more pleasant, but those are sold out and it's way more than I wanted to spend.