The ending was a huge disappointment, and there were several points within the story that they could have made more of, but were simply explained away.
Or all the parts that they glossed over or ignored completely, in lieu of creating new and even more convoluted plot twists.
Like the Calypso thing - what the hell? Could we make a little more sense?
Here's the problem. The first one was the perfect blend of humor and action, a great swashbuckling adventure. The second one, I thought, was a great second act to a trilogy - sets up a few messy problems that will be difficult to overcome, but which can be all sussed out in the last film. The third one, rather than being an effective third act and tying up the loose ends,
ignored the loose ends and just kept cutting more.
You remember the part where the one British guy that's totally crushing on Jack Sparrow says, "Do you think he plans it or just makes it up as he goes along?" That's the way the movie felt - made up as they went along. They thought of a weird effect they wanted to put in, and so they figured out some contrivance to put it in the script.
Plus, the stupid theater we went to see it in cut off the last little bit - everything after the credits was simply cut off and we started seeing the stupid "Who stared in this movie" trivia crap.
Man, that movie pissed me off.
But I feel better now that I vented.