I think an often overlooked attribute, but very important IMO is how a tower, a work of architecture... interacts with light. The various elements in place all play with the light very well. A tower such as thing can't really be appreciated on a cloudy day, but if you get a crystal clear day, with good sun, unobstructed, it really shines as the facade, cross bracing, concrete, and various glass panels and gradations absorb that light, and radiates stunning, intricate details.
Similar tower where light makes it appear much more grandiose is currently Steinway. I expect 45 Broad and 9 Dekalb to exhibit great detail during optimal periods of sunlight.
Comcast Tech Center wins in that respect. On a side note, it also looks good at night too, so thats a plus.