Just got back from theaters watching this.  I have to say, I have mixed feelings about this movie.  It isn't the worse one, but it isn't so great either.  They toned down the jokes a bit in this one.  But if it is indeed Bay's last film, I can tell he's trying something here, although, not great.  Some of the Autobots and Decepticons get very little screen time.   Some more prominently than the others.
I love Frank Welker's voice back as Megatron.  Good times.  Also I think the movie did hinted Unicron.  But I am not sure. 
Overall, I enjoyed the ride.  Hopefully it can be re-booted in which it pays closer to the G1 material.