This primate exhibit is superior to the disastrous new orangutan enclosure at the Colchester Zoo, but that fake rock is distracting. The mock-rock does not appear to be even remotely realistic, and that is something that zoos struggle with all over the world.
I actually like it too, it would just be easier, cheaper, and it would look a lot better if they made that shelter out of wood. Why all the mock rock?!
I have looked at the photo you mentioned (posted by Newzooboy) and I didn't see anything like those wooden boxes in the enclosure last week. The photo was from 2006 though, so perhaps the enclosure has been modified since then?