Lord, the first half of this book is long: not in the sense of number of pages but in the fact that it takes a significant injection of willpower to get through it all. It's by far my least favourite stretch of Tolkien: I'm just not that interested in all the politicking and the epic battles in Rohan - possibly because my favourite parts of The Lord of the Rings are the bits about the weak changing the fate of the world when the wise falter, and Aragorn and Gandalf are pretty much the definition of the wise.
The Treebeard sections are quite fun, though.
The second half is much better (although I know there are fans who find the Dead Marshes a bit of a slog): the relationship between Sam and Frodo is perennially touching, Faramir is quite simply awesome and wonderful (he's the one thing the films got drastically wrong, in my opinion), and Gollum is probably my favourite character in the trilogy - tragic and reasonably psychologically complex.
On to Return of the King!