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'
I watched this today and thought it was beautiful - the animation (the simplicity worked really well for me), sound, everything. It lost its way for a bit around the middle, but aside from that I was captivated throughout.
I really liked it too.
It has an "eastern" style of narrative, quite slow, but always great to watch.
Needs a few re-watches I think, to get all the subtleties.
Really good to see people doing different things in the world of animation.
I watched this again yesterday. Still love it. The scene with the turtle being bashed on the head with a stick of bamboo though upset my other half. I think the animation style is quite beautiful, in particular I noticed for the first time just what a contrast the monochrome (night) scenes are to the colour daytime ones.