School assigned my daughter to read Mrs. Frisby and the Rats of NIMH (1971) by Robert C. O'Brien, so I took the opportunity to read it as well. The book falls into the juvenile talking animal genre, where animals think and act like people, but are otherwise animals. There is little humor in the book, but that's not to call the book humorless. It's more of a drama-adventure, with emphasis on drama.
The book follows Mrs. Frisby, a widow mouse, who finds herself in a bit of a pickle. She can't move because her son is sick, but she must move because it's planting season and the farmer's plow will destroy her house. The solution involves the nearby rats, who don't act like other rats at all, and whose story and plans intersects her own life.
I found the tale a bit slow in the beginning, but about halfway through, when you hit the rat's story, the whole thing got more interesting, leading the tale to a satisfying conclusion. The plot is simple and easy to follow, and by the end, you're rooting for everyone to succeed. Mrs. Frisby isn't a deep character, but she is a woman of sincere courage, which is admirable.
I'm not sure that it belongs among the best fantasy novels of the 1970s, as I'm very torn whether children's literature counts as fantasy. I won't answer that question here, leaving it to better minds than mine to contemplate.