In response to Galt's query concerning the final film in a trilogy not being the best, I offer up two examples that I instantly thought of, that are pretty much at opposite ends of the film genre spectrum-
The final film Red of Krzysztof Kieślowski's Three Colors trilogy was definitely the best (multiple Oscar nominations). I also used to have a crush on Irène Jacob back in the day.
Toy Story 3 dominated that trilogy. Easily.