Your idea here is a good one for this challenge, but I think the execution of it probably cost you quite a bit. I'm not sure how to suggest improving it because I have never tried anything like it myself. I think the color of the fire is a bit weak and it could possibly be stronger with a faster shutter speed making that sharper as well. A little more detail in the background subject would probably bet nice as well :)
:-0 hells that out of focus?!?! NOOOO! loollactually, i really like your concept, the way your set up though it looks like you cut and pasted the flames.