A friend asked me of my experience of this spectacle and I could only say that, albeit having many good elements, it was underwhelming +++ a nice summary actually.
The best thing in the entire trilogy was Davy Jones (as I have pointed out before), and he was so perfect in his first appearance that he couldn't be improved, and there is no new character introduced here that is so appealing, nor any wow-factor element at all, denying the movie any entry in the [visual effects spectacle][pointed] and movie of the year lists. Sure the centerpiece of the movie raises bars, but I'm no particular fan of sea-based action, so this ain't no visual effects spectacle, but it's a satisfactory spectacle nonetheless, for there's a smile on my face when thinking of it, and thinking of its complexities and various treats (and especially the opening scene which is a landmark in film history) [update: 03 Mar 2008].
I mentioned the complexities, possibly a deliberate attempt by movie makers to have viewers give the movie a second look, for there's so much plot, so many betrayals, so many surprises, some disappointments (an annoying marriage; Chow Yun-Fat's appearance), amazing make-up and costume work (nothing new in the trilogy though), proliferation of colorful characters (too many, even for a movie so lengthy)...
Pretty decent entertainment after all, but then I already saw Apocalypto, Fearless, and 300 so far this year, which still stand to be beaten, though none have visual effects matching this pirates movie, and I doubt there will be this year [update], which will result in this being a reluctant winner in that department.