Turning a theme ride tie-in into a continuing series is a dangerous gambit, though it has undoubtedly been a lucrative one so far.
In this installment, very few of the characters from the previous three films carry over. There is a small plot connection via the map that Jack Sparrow has which shows the location of the Fountain of Youth. (Jack's enchanted compass also makes an appearance.) The action shifts back and forth among several groups racing to find the Fountain. The Spanish start first, with the help of a completely improbable and poorly motivated event. But the focus shifts quickly to Jack, sorry, Captain Jack Sparrow, in London to find out who is impersonating him. For those who like the transgendering effect of Jack's eyeshadow, the sight of Penelope Cruz in a moustache will be appealing. Cruz play Angelica, Jack's old flame. Their relationship is highly reminiscent of Indiana Jones and Marion Ravenwood from Raiders of the Lost Ark. With eyeshadow.
Way too many things blow up, too many fights break out for no reason, and too many swords get pointed at the audience just to prove you are watching in 3D. (I was.) Blackbeard is the Monster of the Week, a fearsome pirate with voodoo powers and a magic sword that lets him control his ship. Stuff happens, some involving mermaids. The mermaids are the most original part of the movie. I found Ponce de Leon's ship the most interesting visual, and Ponce himself was amusing.
Oh yeah, it all turns out fine. You wouldn't expect a Disney theme ride to dump its paying customers over a cliff, would you? You wind up where you started, exit to the left, and don't forget your packages that you brought with you. In the next film (and you know there will be one) Sparrow and Gibbs will be fighting Barbosa for control of the Black Pearl - the only lasting theme in the PotC mythology.