I'm not a fan of his facial expressions. That doesn't have anything to do with your photography, but an observation none the less. You really have to direct some models as to what you want to get out of the photo. Some will know what facial expressions are flattering to themselves, and some you'll have to tell. I've worked with a few models that knew what they were doing, and a few that didn't. However, since this is about your photography, I'll stop rambling and get to that.
1. The wall seems to be the center of attention, and he is just an innocent bystander.
2. Again, I'm drawn to the wall in the background.
3. Good composition, and the background is just that. A background. I like this one, and think it's the best of all of them.
4. Variation on #3, and I kinda dig it. It does seem a bit dark, however.
5. Kind of seems like you caught him just as he found a penny. I think if you cropped out the right portion of the wall it would be a bit better.
6. I can't tell you how much his facial expression in this one irks me. I'm not sure why, but it does. Also his hands being folded like that bothers me. Not bad photographic wise.
7. Again, too much wall.
Take everything that I've said with a grain of salt, though. Trust me when I say I'm still a n00b when it comes to portraits and shooting people. Like I said, though, you really have to direct some people to get the result you want.