I hated Pirates 3.
I think you have to look at the genres of music that a composer is trying to score.
Hans Zimmer also scored Batman Begins, The Simpsons Movie and Prince of Egypt. You're talking three radically different genres, still pretty good results. (I assume; I haven't, and won't, see the Simpsons movie.) I think overall, Zimmer is a very talented and accomplished artist, and has a lot of variety in scoring the eclectic batches of movies that Hollywood sends his way.
Howard Shore has been a little bit less prolific. I haven't seen any of the other movies he scored besides Lord of the Rings, but I understand he did Gangs of New York and Aviator.
All in all, it depends on my mood as to which composer I listen to.
Edited to say, Zimmer can't be fully blamed or fully credited for the themes of the Pirates movies, because he was building on the first soundtrack, which, despite being pretty good, had a lot of generic themes and sounds because it wasn't necessarily a big-name composer.