Boring skys are a pain and over cast skys can look blown out because there are no details in them. The problem with this sky is that it grabs attention from him because it is the brightest area of the image. The eyes tend to go towards the object that is very bright as compared to the rest of the picture (or a very dark object if the picture is very bright over all). If there was less of it, it wouldn't be that big of a problem, but because there is so much, it not only drags the eyes off of him but it then highlights the buildings, which are straight lines in the same area.
Maybe you could try cloning in some blue sky and liven it up a bit?
And you are welcome. If it works for him and he is happy, it doesn't really matter what any of us say about it. But everyone has some good points to keep in mind if you get a chance to shoot something like this again. You have a lot going for what you did, you just need the practice to look for the detail stuff, like how his cloths are laying and the background behind the subject. I don't think it would take you a lot of practice shots to start noticing those details before you click the shutter. It really does get easier with practice.
Mike