I don't enter competitions for two reasons.
One is I am afraid of my beers getting bad reviews....my friends definitely are not good beer judges based on them drinking my worst brews.
Second is I almost rarely brew a beer to style. I like to experiment with my beers using alternative fermentables...also a reason why I have had some beers that didn't quite measure up.
I might enter competitions once I get my beer setup fully squared away when I buy my home.