The first movie gave rise to a number of interesting ideas.
The concept that every time a civilization becomes arrogant in its technological progress, a primal beast awakens to destroy it. The idea of a homeless species, unable to adapt to space, longing to get home, and willing to fight for it, even in its most barren and inhospitable form.
It wasn't a masterpiece, but as the first of a three part series it left me wanting more.
The second movie is similar in some ways. The AI of Mecha- Godzilla, surviving for 20000 years and modifying the environment in order to prepare for another assault is a fantastic idea.
Unfortunately, they do not give this incredible entity a voice or character and we are left with the bland, rudderless cast of the first movie to hold our attention. I barely remember any character's name, though there was a vague love arc between the protagonist and...someone else. And there was a super-logical+aggresive species that did a thing (trying to avoid spoilers here)
The Godzilla scenes are interesting for a while, but seeing it bombarded for 15 minutes straight is maybe not the most compelling piece of cinema ever.
Despite that, I'd still recommend a watch. Like I said, some interesting concepts are explored and I'm curious to see what the arc of the native human survivors of the planet might be.