This is a totally stupid ad. Folks with the typical attention span for ads are only going to see Obama talking, ergo - an Obama ad. Cognitive people will remember the excitement of the last Obama campaign and think about his lofty ideals and soaring rhetoric; again, plus for Obama no matter what he's actually doing now..
Subtlety is not going to cut it. Say "Obama has become his own evil vindictive straw man" if that's what you mean. Always say "Romney is better than Obama" in every ad, as directly as possible. Subtle ads will only get lost in the video-induced stupor. Bank on it.