I dropped by briefly this afternoon to take a look. It was surprisingly quiet - I guess it doesn't yet have a reputation to match Dublin's Oktoberfest. (Even though it's just an imitation of the real thing, Oktoberfest in the IFSC each year is a lot of fun and very popular.) The other way to look at this is that the Irish Craft Beer Festival is more of an evening event; for example music starts today at 5 pm.
It's free in today and tomorrow from noon to 7 pm; after those hours and at the weekend admission costs €10.