At the moment the site is still being cleared, groundwork is starting so there is no real construction work to follow... but I did manage to take some photos of the facade cladding test, which looks interesting:
What struck me was the level of extrusion of the grey element here, which looks maybe 500mm further out than the rest of the cladding. The front of the Arena will look especially three-dimensional with all these different layers of cladding.
The insulation(?) looks clumsy here but it'll be hidden behind a damp proof layer, and neither will be particularly visible once the green triangular pieces are added in front.
These green pieces remind me of Alsop's green triangles in Headingley - they are not solid pieces - they are punctuated to reduce weight/add interest etc.