If you have seen the reviews, most Japanese reviewers consider it a masterpiece (probably a little nationalist pride sinking in to their overly complimentary (IMHO) reviews), while many reviewers from other countries consider it a good to slightly above average Godzilla movie.
I found this movie......interesting.
Most people know about the Fukushima disaster from an earthquake and tsunami, but I am not sure what most people not living in Japan know about the details of that disaster.
If you are well read on that subject you realize very quickly what Shin Godzilla is. It's a dark comedy.
The way the government is portrayed and the handling of the situation may strike some people as odd or even ridiculous, and it's supposed to. Others will realize this is pretty much how people believe the Japanese govt. handled the Fukushima situation (poorly).
The SFX for the movie were OK for me. Some of the scenes looked terrible and others looked fine. Some of the changes they made to Big G were interesting.
Overall I would say this movie will be for people either an effective dark comedy or a too talk-y and boring Godzilla movie.
Also there seems to be a 120 minute theatrical release and a 100 minute (international?) release. I saw the 100 minute version and I am glad for it. I don't think I could have handled another 20 minutes of people talking to each other.