This is a good candid portrait; you have captured the subject very well. The eyes are the window to the soul.
It is very seldom that portrait looking up the nose works. That can be most unflattering. Like so many images I see, it seems to be over saturated. The colors look (candy) and not natural, this could be from changing the hue of the image or just over saturation. This would appear to be a very common mistake. Flesh tones are for the most part are not so bright. Toning down the color and contrast would help this image quite a bit.
Nice shot & soft lighting for your candid on the bus. The background seems a little sharp, did you have the aperture as wide as possible? That would give a shallower depth of focus and blur the background a bit so it wouldn't be so distracting.
It seems to be somewhere between a portrait and a candid shot, but I think it would be better if the photo were closer to one or the other, but not inbetween
Appears he was about to speak, the capture leans on the side of candid. Exposure is good, may concider dodging the eyes a little to bring out their sparkle more.