In re-reading this, I discovered what I'd forgotten - what a consummate literary writer Simak could be. This story, while it's about an invisible barrier and the aliens that create it, is a classic exploration of small-town America. Extremely readable, with likeable characters that consider problems the way you and I might. The language and story aren't zippy action sequences, but flowing prose about real people. This story reminds me of Jack Finney, a rough contemporary of Simak's.
Definitely worth reading if you like intelligent writing.