The New York, Boston, and Philadelphia subway systems' station architecture is bare-bones functional. They didn't spend a lot (any?) money on making it look pretty. The Washington Metro is different. Someone decided that they needed to pay attention to the design, as well as the function.
The function works well enough. The design, however, couldn't have been worse if they tried. It's like they told the architect to make it as dark and foreboding as possible. Everything's concrete, and lit from below. The effect is overwhelmingly evil and oppressive. I suspect it won lots of design awards.
I'll use it, but I really wish they'd gone for something more friendly in appearance.