There aren't that many beers that I haven't had before / are super-keen to try, but there are a few... and I guess that's enough. I'll be going. I won't go on about sessions, entertainment, food, and ticket prices. You can find that easily at the fest's site & make your own choices: http://www.peibeerfest2013.com/
What I will do, however, is just give you my own personal spin on what you should try to sample first (at my own peril, since I'm not going on Friday - I'm going for an easy-going Saturday afternoon), brewery by brewery. Just my own two cents, just in the order they appear on the fest's site.
PEI Brewing Company
Feel free to try them all (the only one I avoid is the Island Red), but, if you're an Islander, you have them available to you all the time. Go for the Spanish Cedar IPA, a one-off for the fest. If it's anything like Flying Monkey's Matador - an Imperial IPA on cedar (I'm betting this is what it was inspired by), it could turn out really well. Once listed was the Pumpkin Ale (which will be in bottles and on sale soon), but it's no longer there.
Mill Street
I'm curious to try the Curious Parrot & especially the Don Valley Bench, given what Jason Foster's been saying (that it's like a Chardonnay). I'd rather try a sample than buy the seasonal six-pack.
Moosehead
I'm very keen to try the Cask Ale, as I've heard good things. I might also try the Boundary Ale, just to see if it's much different in the bottle vs. from a keg.
Picaroons
Near the end, I may try the Blonde & a Dark & Stormy Night, just because I haven't had them for a couple of years. I'll avoid the Yippee IPA as the last bottle & pint I had of it were both butter bombs.
McAuslan Brewery
I'll probably have an Apricot Wheat, as it's an old fave, and I haven't had it in a while. I'll probably also have the Pumpkin Ale again (it's been a while), and would like to retry the Pale Ale - others say how good it is, and the last time or two I got it in the variety cases here, it wasn't worth commenting on.
Garrison
Might sneak in a Hop Yard - been too grassy / spicy in the last couple of years, though. Not as much citrus / evergreen anymore.
Sleeman
I might try the Fine Porter, just because I never have, but you, if you've never tried them, should try the three Unibroue beers we have in stores: the Blonde, Blanche, and Noire de Chambly. The first beers to be sold in non-novelty large format here, and all good ones at that.
Amsterdam Brewery
Quite eager to try the Boneshaker IPA & the Oranje Weisse, as we don't have them here. Also looking to sample the Natural Blonde, because, even though we have it here, I haven't tried it yet.
Pumphouse
I've heard about people going back to the red recently and being pleased. Might have to retry it myself.
As a closing note, you should try the Mort Subite Kriek if you haven't yet. It's the only lambic / sour beer ever sold on PEI, and I'd love to see more of this style come in. Expect it to be fruity (kriek = cherry), a bit tart, and slightly woody. Others we have that you should try if you haven't: Affligem Blonde, Paulaner's Hefe-weissbier, Erdinger's two beers, the Creemore Lager, maybe Amsterdam's Big Wheel, and, heck... even Keith's two single-hop beers to see how different hop varieties can be.