In the year 2000, one year after the Babylon incident. A mysterious creature has been spotted in the Tokyo Bay destroying fishing ships and patrol boats. Two detectives are on the case, and try to gather up clues on the mystery. As it later turns out, they're dealing with a biochemical monster that can only exist by being made by a human. And their yet to find out who's responsible for it's existence before it destroys Tokyo.
Unlike the previous Patlabor anime. This one revolves on 2 characters who aren't part of Special Vechiles Division 2. But it does take place in the same universe. Only we don't see too many Labors at all. And every one we know from Patlabor are only in 1/4 of the movie. With the exception of Captain Gota being the only original character having the most screen time. While everyone else is a minor character in this movie.
Making it not look like a Patlabor movie at all. Despite it directed by someone other than Mastu Ohjii and newer animation. This is consider to be the weakest in the Patlabor series. Not saying it's bad at all. Just the director failed in giving it the same spirit as the other movies and TV shows.
It's more of a Monster anime flick than a Mecha anime flick.
If it was directed by Ohjii, then we'd see it as the same level as the previous movies. That and it's more of an in-between movie than a sequel cause it takes place between the first 2.
Overrall Patlabor WXIII does succeed in having believable characters, actions, drama, and locations. If your a fan of the franchise, you might not find this one to be satisfying.