I really liked the Spiral vs. Anti-Spiral concept of this 3rd arc.
The apparant allegory is simple, but not pushed down your throat.
Spiral = DNA = Life
Anti-Spiral = Space and Time
It seems to be saying that the only way to progress life is to battle space (the environment) and time. Rage against the dying of the light sort of thing. It’s often the theme of this sort of robot show, but the 3rd arc of G-L seems to boil it down to the essence and make what is normally just the theme a physical aspect in the show’s world.
I read somewhere that they are dropping the 3D CG for the rest of the anti-spirals. I hope that’s not the case as it was a neat visual trick, as well as commentary of the animation trends of the post-Eva anime. Though maybe there will be new visual metaphors for this last arc?