The only possible fantasy power are the visions of Fiver, who gets the whole exodus started. Here and there his precognitions help the rabbits, although you, as a reader, never get any firm nod towards this being an actual power or not. The magicness of this is left in the air. (You may feel free to disagree.)
There is some good fantasy in the novels in the tales of Al-Ahrairah. Told as trickster tales, Al-Ahrairah and his best buddy Rabscuttle has all sorts of wonderful and engaging adventure stealing carrots and tricking his foes. These stories were so well told that my daughter, who would have thought the rest of the story tragically boring and uninteresting, reveled in the cleverness of those stories. If you want to just crack this old book and read those stories, do so. You'll enjoy yourself.
The books is also a documentary about rabbits disguised as an adventure story. And pay heed, you will learn heaps about rabbits and how they act. They do all sorts of things that I never imagined. And who would? (Rabbit people, I guess.) Richard explains their behaviors in clear detail without ever overburdening you with the explanations themselves.
The story itself is well written. It begins slow, but with the introduction of the Big Bad, achieves a much higher tension and moves itself along more tightly. General Woundwart is exactly the kind of villain who chews the scenery, which is very appropriate for rabbits. He has all the motivation for acting as an unstoppable force, no matter how stupid that might be. To be honest, I really got fed up with that villain being so mind-numbingly single-minded, but at least his minions had enough sense to be less thrilled than he was. Even as a rabbit villain, his minions were still rabbits and acted like rabbits.
It's my understanding that Watership Down is a much loved and respected novel. I understand that and I do not diminish this for anyone. For myself, I will never read this book again. I reach the end with a feeling of relief, much like a man freed from jail. If fate forced me to choose, I would reread the Sword of Shanarra before I reread this book, and that's saying something. However, it's not at the same level of never-again as the film "Dancer in the Dark," which was not only indescribably excellent, but totally impossible to rewatch due to the excruciating level of psychic pain.