I haven't been in a few years, but I don't think it changes much from year to year so this is probably all still valid:
Expect an impossible assortment of incredible beer. Like, such a volume and variety that prioritizing or trying everything you want is impossible.
They'll give you a little book at the start, your tokens are printed in the back. The tokens are a technicality, there's no way to use them or buy more. Unlimited sampling.
There generally won't be lines other than at the Goose Island booths and when the awards are handed out people rush to the winners.
Food on site sucks.
Looooooong line to get in when the doors open.