Attached Link: Help on a WIP

Working on a new scene called Disaster In The Hills and can not figure out what the scene is missing. I just can't seem to put my finger on it so I thought some of the talented artists here could help me out. I know the smoke is not quite right and the tree looks too fake but I am dreading re-rendering. It took 1 hour 23 minutes and 15 seconds (using a comp with 2.8 ghz processor and 512 mb ram). However, if someone can help me figure out what the picture is missing or has any suggestions I will fix and re-render.

Thanks