While I really like the ending and the sense of finality, I really don't care too much for the movie as a whole. I mean, it's definitely not the worst, but I wouldn't rank it among my favorites. The connections with the original "Mothra" were fun, especially Hiroshi Koizumi as Chujo, but it reeks of lost potential.
One thing I didn't get is how Chujo could identify Mothra's weapon of last resort. If "Mothra vs. Godzilla" were in this continuity, it would make sense, but that's clearly not the case. Oh well. I think I'll live.