The outcome depends on your OG & how much yeast missed the opening. If it's a low gravity beer and you only spilled a little, I wouldn't worry about it. But anything over about 1.060 and/or a lot of yeast missed means the yeast will likely be stressed, and that can produce a lot of ester-y flavors. If that's what you're looking for, again no worries. But if you want a nice "clean" tasting beer, you may be a bit disappointed. Most yeast-derived flavors are produced in the first 12-18 hours or so, however, so it's probably not worth pitching more yeast. The ones that made it in have multiplied and will get the job done.
Good news is, you'll still have beer. And it's not likely to be catastrophic... Maybe just a tad off.
