Fantastic special effects don't make up for what is generally a confusing film.
A storyline that is never quite clear, sub plots (one lasting about 20 minutes) that have absolutely nothing to do with the main storyline, and nowhere near as much humour as the first film - make for this a poor sequel to an excellent first film.
The whole film is dragged out far too much, so as to leave enoug story for the thrid installment in the trilogy.
Your kids will probably love it, and in it's own right it's not a terrible film it's just let down because the first one was so good.
Worth a watch for the special effects and Johnny Depp alone (and Keira for the guys) but don't expect any oscar winning storylines or stright foward plots.