I did YC summer 2009 (Bump). Of the 3 founders I was the most critical going in, mostly based on valuation. But unlike most investor relationships, the money is the minority part of the value provided. The majority is things money can't buy: advice/perspective, encouragement, the front row seats mentioned in the article, multiple networks, more. I didn't fully appreciate the quality of the intangibles until later. Now my advice is- if you can get in, just do it. Some people go through twice I hear, what is that saying.