Like the most overrated first film this sequel was also average at best in terms of action, plot, acting etc stuff and the only reason u should watch this once in a theater or in blu ray at your home is the outstanding new technology improved special effects.

Leave that out and this film will be forgotten like the original.

Another flaw is this film was too long and at times it was like we were watching doc from national geographic or so.

If we wanted to watch those endless underwater scenes we could watch docs like frozen planet or the blue planet parts 1 and 2.

So just to admire the great special effects u can watch this average film once and then send it in to the oblivion where it belongs together with the first film which may be a top grosser film but it was also voted as the most overrated commercial successful film of all time.