Birds and shapes are very slapped on and don't mesh with the work as a whole (especially those balls). The lights are similarly out of place and the soft brush lighting doesn't look all that good.
The dissolving particles are the really important part of this piece, though, and that's where I think you went a little overboard. There's simply _too much_ going on, which makes it look less like the person is "dissolving" and more like you just went overboard with splatter clipping masks and the smudge tool. A few tips that might make it look better:
-Don't have the dissolve happen everywhere on the person. Keep their head clean and probably one other side of their upper body (first glances say left shoulder); this accents the fact that the dissolve has an intended purpose and is slowly spreading along the body.
-Less is more. You don't need so many dissolved particles to show that it's actually happening. Show that the dissolved particles are moving away from the person, and even if you have half of the particles you do now it'll be easy to understand what's going on.
-Don't blur the edges. The right shoulder is an especially big offender of this rule. By blurring the edge of the person, it becomes harder to define borders and makes the effect seem messier than it is or should be.
You just have a lot going on in this one piece, a lot of which doesn't make sense for the concept you're trying to get across. Clean it up and you'll see definite improvement.