I picked Cleary's book as my first Newberry book because as a child I'd read and loved just about everything else she wrote. I never got around to Dear Mr. Henshaw though, probably because I was already in high school when it was published.
Dear Mr. Henshaw is mostly an epistolary novel in which 10-year-old Leigh Botts is writing to his favorite author. Then, the author tells Leigh to start a journal, which mkaes up the rest of the novel. This book is terrific; it's a quick read and very funny, but addresses timeless issues for children--being the new kid, losing a parent, pet, or lunch, and finding your voice. There's lots of sly Cleary humor that I enjoyed as much now as I did when I was nine. Leigh turns up in another book, Strider, which is the name of a dog, not to be confused with Aragorn--although I'd read Cleary's version of Lord of the Rings in a second. I think Ramona could have taken care of the bad guys in fewer than three volumes.