In short,
Lot's of Piracy going on makes the story jump around a bit.
Keith makes an interesting pirate.
If you liked the other 2...go see it. If the 2nd one was too much for you...then maybe you should save your cash.
Visually it was well done. Great effects.
If you go...stay through the credits.
I liked it. But then again, mindless entertainment is what I go to the movies to see:-)