I've gone to this (as well as the fall session in Durham) for most of the past 4 years or so. I've always hit the afternoon sessions after numerous warnings that the evening session can be a bit like a drunken frat party. Apparently, only the most responsible people drink in the early afternoon.
Plus, it is common for some breweries to completely run out of beer during the afternoon session and have nothing to offer in the evening. So, calmer setting and more varieties available.
Anyway.... The fest was always a reason for out of town friends to come into Raleigh so we could hang out for the day, but I don't have out of town friends coming this time, so I'm not attending this time.
edit: the festival is pretty good. It does get crowded and, depending on the weather, can be quite stuffy in the tents. Food is kind of expensive at the festival.