Excellent post by MJ. Pretty much sums up my feelings.
I do love the design, and while not sold on the exterior, I feel if clad well it could really look sharp.
My only real gripe is that skyline composition-wise, the location is poor for this specific design and height. That said I'd rather learn to live with it than not have a building of this caliber go up.
Just for shits and giggles, I threw together a crappy rendering of what this tower would look like between 19th and 20th on Arch, if the ACC had been built on the 18-19th plot like originally proposed.