The strong vertical of the window frame on the left I find to be rather distracting. I think this would be easily solved by cropping the black sliver off of the left so the frame runs off the edge of the shot and just looks like border, not like a freestanding strong vertical line.
And more importantly, the drink cup on the ledge is immensely distracting. Moving it out of the picture would have been good. Either that, or buying the girl a drink so that they both have a drink and it's kind of a joke hehe. As is, it's in a low detail part of the image and cloning might also work, though.
Besides distraction, the composition is quite strong, though, and interesting.
I agree, the composition is strong as it is, removing the dark vertical breaks the balance immediately. And the cup adds to the contrast between large and small here. I would have photoshopped the light spot in the top left corner below that tiny light, it would make the light itself more visible.