This book and its trilogy are good, but I've read better books. They're not everything the Tolkien nerds make them out to be. Comments:
-Tolkien's writing skills are not great, just okay.
-I did not expect what happened in the last two chapters of Return of the King are unexpected, and the ending was puzzling.
-The issue of Sauron is very frustrating. Sauron never personally appears in Return of the King or the entire trilogy. He is only spoken of. He amounts to some very bad man who wants to find the One Ring, which will allow him to rule Middle-Earth.
-The characterization in Lord of the Rings is limited; some characters have depth, but others are cardboard. Legolas is the most shallow character, being nothing but an elf who travels with the Fellowship, occasionally speaks, occasionally fights, and banters with Gimli the dwarf.
-Some Goodreads reviewers grumble that the relationship between Frodo and Sam becomes homoerotic. I really think that is overstated. Sam is very affectionate, but after the part of Return in which he rescues Frodo, he doesn't act like that so much; and near the end, Sam marries a female hobbit, so he would not seem to be gay.