There was so much of hype for this movie, but in the end it failed to impress me.
It's the classic case of "Great Cast doesn't guarantee you a good movie".

The cast of this movie was quite impressive and to be fair, all managed to do a very good job as far as acting is concerned. But when you stuff all these magnificent actors in one single movie, there's high chance that the script is not gonna do justice with all of them.
Can't blame the efforts of actors, though. Han Hyo-joo was very beautiful as a pirate, and so was Kang Na-heul with his witty lines and erratic behaviour. But the one who impressed me was Lee Kwang Soo. It seems like he simply can't leave behind his image of being a betrayer behind (*pun intended).
There wasn't much to do for Kwon Sang-woo and neither for Kim Sung-oh, which was kind of a bummer as I was really looking forward to their roles, only to be disappointed at last.

Now coming to the story.
It was just awful. Characters popped out of nowhere. There was no backstory for Han Hyo-joo and was very weak in the case of Kang Na-heul. It was just the plot of the previous movie, albeit with a bit of new ingredients. Let's compare it with its prequel:-
A Pirate - check
A disgraced soldier turned bandit - check
One evil general - check
One betrayer - check
And animals rescuing the pirates - check
The story might have been good if not for so much of stuffed characters. Chae Soo-bin's character literally had no importance at all.

At last, I will say some words for the VFX. It was childish graphics. Yes, the VFX certainly improved in the last act, but overall they were very poor and one can clearly see that there are just a lot of green screens.

Overall, I was disappointed with the movie, but the cast made it a bit enjoyable. Watch it for Lee Kwang Soo, Han Hyo-joo and Kang Na-heul. If you are seeking a good story, then don't go in that direction. Better to leave your brains aside while watching this movie, as this is certainly very logicless.