This is the first in a long line of German-themed episodes. It's a well-written hour and it showcases the 'family and friendship' theme of the series very well. I particularly liked the scene with the children in the treehouse.
Given how religious they are, the Waltons seem incredibly open-minded in this episode, even allowing their children to go to a Jewish service. Contrast this with their reaction when Jason's girlfriend tells them she is Jewish in a later instalment.
The Manns are typical Hollywood Germans. They speak near-perfect English yet feel the need to say 'ja' at the end of every sentence. Walton's Mountain seems a strange place for them to hide. Surely they would be better off in a town with mixed heritage rather than a village where everybody is of British descent? Interestingly, Eva is played by Will Geer's daughter: I didn't think that accent was real.
It's a heartening story though, and it's a shame we never see any of them again. Perhaps they decided America wasn't for them.