Well, having 191 different colors on the palette would make it hard to believe it was all hand pixelled.
Not to mention that most of them are really close and unless computer generated, doing that would be a waste of time (esp. if it the whole thing looks like it has 10 colors at most).
Though the AA doesn't work where the building meets the white BG nor on the black lines on the top.
As for the windows, you should notice that the reference photo and your picture have different views, so if you want the whole thing look like it's angled inwards, you should tilt the straight sides too.