I've said it in every other post about these books so far, but I will say it again: you should read The Lord of the Rings. If you haven't read them, then a) I'm very sorry for the sad life you have heretofore lived, and b) you should read them immediately. If you have read them, then you should reread them. These are the kinds of books that spoil you for everything else that isn't nearly half as good as they are.
There is a fair consensus amongst those who come to consensuses about such matters that Tolkien wrote The Lord of the Rings primarily as a way of exploring Middle Earth - that is, this is what is known as a milieu story, in which the setting, the world, drive much of the plot. In The Two Towers this is on fine display again. One of the more interesting things to do with a copy of The Lord of the Rings is to sit down and look at just how much ground is covered by the various journeys; you then realize just how large a world Middle Earth is, and how small a section is explored in these tales. The distance covered by Frodo and Sam through such great peril and difficulty in the entirety of their chapters in The Two Towers is essentially a tiny corner on the map.
If you've been a follower of the site for awhile, you may remember the post "Written in a Corner." In that post, I mentioned that I would write another post addressing the topic of plausible impossibility, which is an important concept in speculative fiction writing. Of course, if you've been a follower of the site for awhile, you probably also have realized that I'm not always very good at following up on these post ideas that I drop in my posts in anything approaching a timely fashion. Don't worry, I'll get to it eventually. In this case, it's only taken me a couple months.