I've struggled with similar shots in the past. The issue I've had, which I see here, is getting the subject (those in focus) to pop out and separate from those in the background (not in focus). For me, this one just isn't quite there because of that. What can I say? I need it kept simple.
For me, finding good shots has been harder because I need to create more space between subject and background, meaning I can't usually shoot straight down, but a lot closer to horizontal, making it much more difficult to have a solid background.