Peace, love and destruction...
Like Godzilla's Revenge, Godzilla vs. the Smog Monster devotes a lot of time to family-related subplots, character exposition in their leisure time and to its thick procedural. Attempts at dark photography to bring back the sinister vibe of the original Godzilla have been noticed in the past. This is one of them. Having the creatures fight at night works well on a horror level.
This may be the goriest so far. Although blood is absent, we see explicit on-screen human death. The chaos it provides could only be imagined, prior. Another novelty is the artistic editing: a mix of narrative frame by frame animations and transitions that just don’t blend well with the rest. Even the child protagonist doesn't justify such infantilizing, considering this is a drama; not comedy.
It’s not the best in the franchise and it’s not the worst. It is a "versus", not a battle royal. This one could be labeled the "hippy Godzilla". While it hits a bottom when it becomes a musical, it tries hard to update itself but forgets how strong a franchise it is supposed to pay justice to. It is, at times, simply too left field for its own good and you'll wish there wasn't as much dialog.