This movie is HARD to review, if anything it is a prime example of a 'mixed bag'.
At first the good stuff: The premise of the movie is downright genius. The design of the world (not the character design, later more on that) is wonderful and complaining whether it is steam- or diesel-punk is nitpicking. There are many ideas/designs, that made me downright jealous, why I did not come up with them. At some points I even wanted to point at the screen and say: "They put this historical character in this situation? Awesome!" or "Oh, look at this!", especially when it came to the creative background art. The opening-sequence is wonderful, too (the song accompanying is not). And finally, I enjoyed the action-scenes, despite all the issues the movie has.
It is a decent action-flick if you don't have too high expectations.
Having that said, here the bad things:
Animation: First and foremost, the animation of the characters is bad, 1980s-western-television-animation-bad. It is clunky and the characters convey less emotion, than the puppets from the Thunderbirds T.V.-Show. The phoned-in voice acting does not help either.
The bad animation attributes to some serious blending issues the film has. Especially the bad character animation does not go well with the rest of the film. WOTW Goliath feels like the teams of CGI-, classic animation and 'rest' did not communicate at all. CGI is passable.
The character design is poor. Many characters have the same stereotypical body-type repeated over and over again. You will also notice that some of the men apparently have their shirts directly painted on their skin.
Writing: Although there are some fun ideas in the movie, the writing is something between bland and bad. Many lines and actions stood out as stupid, forced or contrived. You know that you in for sub-par writing, when someone drops the line "As you know..." and then spills exposition to an audience that already knows these facts... an exposition, mind you, that was already perfectly conveyed to the viewer in the 10 minutes prior.
The movie devolves into "fight fight fight", with no real character-development after the point the martians have landed, but I don't complain about that – that was what I wanted to see after all. I would guess that this movies was originally planned as an OVA or series, but then got cut down to the length of a movie.
Direction: There is one thing that really ANNOYED me: In nearly every shot of this movie the camera is either panning, zooming in or out and/or tracking somewhere. Often this establishes something the audience has already seen before. This annoyed me so much so, I had to think at the 'slanted angles' from Battlefield Earth. I even assume that some people might even get motion sick while looking at it.
Conclusion: "Force the Guillermo del Toro to do his take on this."