From what I heard, the majority of the film is
produced by traditional cel animation.  Certain
scenes did require digital ink & paint combining
with more CG effects.
Anyway, AMG movie cels are going to be more
expensive than the OVA cels.  I cannot wait to
watch this movie, hopefully, it won't be a 
disappointment like the Escaflowne movie (some
people love it, but I don't like it much).