This was one of the books that I had to read for English class as a high school freshman, but actually liked. Adams created a believable rabbit society, with its own daily concerns, natural rhythms, social hierarchy, and mythology. The characters talk, but they otherwise act and think as rabbits might be expected to. Returning to Watership Down as an adult, I found the story just as engaging, with likable protagonists, scenes of danger and battle (which had helped hold my 14 year old self's attention), and several different rabbit cultures. For a 1972 novel, it remains pretty timeless, though the absence of significant female characters may feel odd to modern readers.
The audiobook narrator isn't a standout, but he does a decent enough job.