The Elfstones of Shannara is, in my opinion, the best of the Shannara books. Terry Brooks has exorcised the need to imitate Tolkein, and is now free to explore a somewhat different – and more original – story. While he does not succeed in creating a classic that will ring down through the ages, he does manage a reasonably enjoyable fantasy novel.
Unfortunately, reasonably enjoyable is still pretty flawed. The main issue in the story is whether the main character can access and use the power of the Elfstones. The answer is generally no, or at least not yet; eventually the threat grows to the point where their power can be accessed to smash the opposition and the quest continues. Once the reader has figured out the pattern, there’s not really much sense of threat. The quest is pretty much a standard “take the McGuffin to Mount Doom”, conveniently handed out by a Druid with very little backstory.
All that said, this is probably the best of the Shannara series, and a good place to start with Brooks to see if you will like him as an author. There is very little connection with the first book in the series aside from one recurring character, and the writing is better than The Wishsong of Shannara. All three have basically the same plot with different McGuffins.