Poor Jane indeed: I tend to agree with Mr. Knightly's opinion of Frank Churchill, and can only hope those two find happiness despite some very unpromising beginnings. Then again, I'm not the world's biggest Emma fan, so the same could be said of her marriage as well. At least Emma and Frank both acknowledge they're the lucky ones by the end of the story.
One of the things I like about Austen is how she provides fairly believable character portrayals: they have flaws and are imperfect, her villains still have likeable and even good qualities, couples who love each other sincerely still have challenges and disagreements. I think that's why these vignettes can convey a lot even in small packages: Austen provided such vivid templates that they're fun to write and read regardless of how much or little we get from them.