Earlier this month, Criterion released Watership Down to iTunes; a full Blu-Ray/DVD release has not been announced at this time, and Criterion's own site doesn't list it as yet part of the collection, even as "coming soon". [Tip: InkyCrow via Newsbyte]
If this does make Watership Down part of the Criterion Collection, it would be only the third animated feature in the collection, after Fantastic Mr. Fox and the no longer available Akira.
The movie is an adaptation of Richard Adams' bestselling novel; it's main competition was in the bestsellers list was Peter Benchley's Jaws, which it beat, despite being about rabbits. Though both novels were later adapted to movies, they didn't directly compete at the box office, which is probably a good thing for Watership Down.
It was directed by Martin Rosen, who went on to direct a second Adams adaptation, The Plague Dogs. It features the voice of John Hurt as Hazel. Hurt is probably best known for his memorable role in Alien as the ill-fated Kane, though he recently played the 8 1/2 incarnation of the titular character in the long running BBC series Doctor Who as the "War Doctor."
The rabbits of Watership Down speak their own language, words of which have been known to be repurposed by furries.
Update 2/1/2015: Watership Down will get a full Criterion DVD/Blu-Ray release on Feb. 24. [InkyCrow]