Hi there, Californian visiting. I'll be in Portland with my wife the weekend that this festival is going on and we're considering attending. Hoping to get a locals take and see if it's worthwhile. Thank you!
I went last year, it's kind of your standard beer festival. The selection is pretty evenly split between international, national, and local. Not much is going to be exclusive or rare or anything if that's what you're looking for. Portland festivals are typically token-based, where you pay a fixed price for entry and a few tokens, then additional tokens are usually $1 each. This one follows that model, and I find a lot of beers, especially international ones, cost more tokens than they should. Samples are something like 3 or 4 oz and a couple booths (Machine House last year) will do full pints for 4x the tokens. Basically if you just want to sample a bunch of PNW breweries, it's an efficient way to do it. You'd probably have a better experience visiting breweries in Portland, but you'll get to try less things that way.
I've been to this a few times over the years and it seems like the selection has gotten progressively worse (and the overall vibe isn't far behind). I told myself last year I probably wouldn't be back. It used to be that they'd have some rare things on draft or in the bottle but a quick look at this year's list - both international and local - makes it look like almost everything can easily be found at local stores. I feel like they should just ditch the local and go all international (I mean aren't there enough beerfests dedicated to local beer?) but since they seem to no longer get anything from Shelton Bros. there's probably not enough product for that. If you want to sample a bunch of local stuff there are local taprooms with a ton of taps (Loyal Legion for instance) that are way better deals.
TL;DR version: Being in the PNW IS a beerfest unto itself. Chillax, there will be great beer everywhere.
I second what @beertunes said. The bar crawls suggested in the visiting Portland thread will give you a much better sense of drinking in the PNW.
@shelby415 and @weaverr pretty much nailed it. I think I last went 3 or 4 years ago and haven't been back since ( just for the reasons @shelby415 mentioned). The commentary and recommendations made by @beertunes and @DefenCorps are spot on. Cheers!