Loved the Penderwicks. The book has such an old-fashioned feel (including the cover); I think though adults might like it because it reminds them of their own childhoods, kids will still enjoy the adventure, humor, family relationships, and romance. Perfect summer read. 
 I was a tiny bit thrown off by an unclear sense of time. I imagine the author wanted it to be modern but timeless, but there were only a few things that set it in current day, which almost just made it more confusing. There's no reason this story couldn't have happened in present day, but it mostly seemed like it wasn't.