I bought the BD a few days ago, on the strength of rave reviews in the Observer, etc.
TBH I was disappointed. The story isn't much, and the animation on the whole is less interesting than that from Studio Ghibli (this movie is NOT animated by Ghibli) or other Japanese anime movie makers. There is rather a lot of boring texture filling the screen in many of the shots.
There is no dialogue (I knew that, but it does not help to make it any more dramatic or to make it clear what is going on.) Not much characterization.
I suggest you try 'My Life as a Courgette' (European stop-motion animation) or 'Letter to Momo' (under-advertised Japanese anime) instead. I bought both recently and liked them a darn sight better that 'The Red Turtle'