Has anybody else ever been struck by how horrible a person Emmy is, not only her actions themselves but also just how terribly written a character she is?
She places the Dorats on Lagos Island, thus birthing King Ghidorah and causing the deaths of hundreds, if not thousands of people before Godzilla kills KG, she also (indirectly) causes the creation of the new Godzilla, she also flirts with her distant relative constantly despite him having a girlfriend/fiance and of course being his RELATIVE, and when she travels into the future to create Mecha-King Ghidorah, she doesn't return to 1992 until like 15 hours later, allowing Godzilla to first go on a rampage causing billions of property damage and many innocent lives before finally showing up to do anything about it.
What a shrew!
Then there are also just the terrible writing issues with her character: why would she agree to go back in the first place? You might argue she had been lied to by Wilson, and that he said they were gonna go back to warn Japan of the consequences of unbridled capitalism that would lead to a future wherein they dominate a world that hates them for it....but then why would she go along with the rest of the plan? Why would she go along with the Godzilla facade? Why would she leave the Dorats on Lagos Island? What was the original plan from which Wilson deviated that caused her to become so disillusioned and angry? What causes her to chastize Miki for being overly sentimental about changing history and then two seconds later going through the same thing with Wilson?
The Emmy character is ATROCIOUS, as a person and as a plot device.
She's a HUGE part of the many problems I have with this film and....well, I don't wanna open the can of worms with my beliefs about the time-travel stuff here, AGAIN, but hopefully we can leave it at: the disastrous writing with the Emmy character is the reason I just can't bring myself to believe what most people accept as the truth about the time-travel stuff (ie, Keith's SFJ article).
All of that long-winded stuff said, the tl;dr version is: the second half of the film's not bad, but the first half is horrid. Overalls it's an uneven film, but relatively enjoyable.