I don't get excited till we get to the home stretch, which is usually about 4-2 months before release. It was the same for ROTF. ROTF might lower my expectations a little, but hey it's Michael Bay I never had great expectations going into the previous TF movies, Just seeing TF's on the big (or really big) screen got me excited. If the third movies crap and we get to a fourth movie, then hey by then the novelty might be gone, but it's not gone yet.
Besides generally speaking IMO TF fiction has been declining all across the spectrum these days.