Spoiler: I didn't like it much.
Ninkasi Brewing Company of Eugene, Oregon is another northwest microbrewery that strives to make a better beer than the average Budweiser/Coors/Miller/whatever. I decided to try their Vanilla Oatis Oatmeal Stout and I had high hopes. However, I think the vanilla detracts from, rather than enhances, an otherwise-decent stout.
Image credit: RateBeer. My opinion seems to dissent from the majority there.
It isn't an extremely obtrusive vanilla flavor, thank goodness. If you like a hint of vanilla in everything, you might like this. I like a good stout, so I don't like this brew. It doesn't appear that they make a basic stout, either, so I'll stick with Guinness Extra Stout or Deschutes Obsidian Stout instead.