Obviously he's mainly famous for Watership Down, and rightly so as it's a classic. As with all books nominally classified as children/young adult literature there's probably an optimal age to read it, maybe early teens. I think I was probably about fifteen when I picked up the old Puffin edition (pictured on the right) that my parents had had lying around on a shelf for years, but I can't really remember. Many people's recollections will have been coloured by the 1978 film, and if I'm honest I couldn't swear with complete confidence which order I encountered them in, i.e. I might quite possibly have seen the film first. The loathsome Art Garfunkel song aside it's actually pretty good and a very faithful adaptation of the book.
My other reason for writing this post, though, is to steer you away from Watership Down and onto some other stuff. Looking at his slim list of novels I actually find I've read all of them apart from the last one, Traveller. All of the ones I've read are well worth a look:
- Shardik is a dense and complex fable set in an imagined world (map reproduced here) which would have been intensely reader-repellent to probably 90% of the people who read it thinking it was going to be Watership Down with bears. Adams apparently considered it the best thing he ever wrote, and he may have been right.
- The Plague Dogs is probably a bit more in the young adult-friendly vein than Shardik, and it's very good, and was also filmed. I haven't seen this one, but unusually they changed the book's happy ending for a more downbeat one; usually it's the other way round. This is really the only one of Adams' other novels that reads like an attempt to write something similar to Watership Down; it's certainly the only other one to feature anthropomorphic animals (the bear in Shardik is less central to the story than the cover art and blurb suggest and is utterly wild and unpredictable), and it's really the only other one that'd be suitable for, or comprehensible to, children and young adults.
- The Girl In A Swing is a complete departure from any of the other books: definite adult theme, no animals of any kind. It's a sort of queasily erotic mystery story with possible supernatural undertones. I had no idea until five minutes ago that this one was also filmed, in 1988.
- Maia is a sort-of prequel to Shardik; like Shardik it's really a book for adults, not least because there is quite a lot of sexy sexy times in it (cover art featured here). For a book of over a thousand pages it's a hoot to read and I've done so at least twice. No necessity, in my opinion, to have read the much more gnarly and complex Shardik first unless you want to; this one is much more of a rollicking adventure story. It also features the only fully-realised and convincing female characters in the Adams oeuvre; the females in Watership Down, for instance, being an afterthought and only brought into the new warren be impregnated by Hazel and his chums.