Prequels almost always cause retconning, either intentionally or by accident. But this is comics, and continuity between movies isn't what you'd call a "priority." Yes, this is technically a sequel to 2017's "Wonder Woman" which was set during the First World War, but Wonder Woman also played a major role in "Justice League" which was set in 2017. So going back to 1984 is effectively "history" to another canonical DC movie ...
Gal Gadot returns as Diana Prince / Wonder Woman. Chris Pine returns as Steve Trevor - which is interesting, because he died near the end of the last movie (and would be approximately 100 years old had he lived). But again, this is comics. The MacGuffin in this movie is the Dreamstone, which surfaces at the museum that Diana works at. It's tended by Barbara Minerva (Kristen Wiig). Both of them make wishes of the Dreamstone without realizing what they're doing. Then Max Lord (Pedro Pascal), who knows exactly what the Dreamstone is, steals it and makes things far, far worse.
There are a couple long sections I felt were unnecessary. The first was a flashback to Diana's childhood to establish her belief in fairness and justice. Umm, hello? What the hell else has Wonder Woman ever stood for? Which means that this adds to the run-time (a painful 151 minutes) without telling us anything we didn't already know. And the other section, while at least a part of the main plot, is the film making fun of Steve Trevor's lack of understanding of modern technology - including his enjoyment of fanny packs and parachute pants. Kinda pointless, and not as funny as they thought it was.
This also ties into another logical problem. We've clearly established that Steve doesn't know anything about technology after 1918 - and yet he climbs into a 1984 military jet and works out how to fly it in about five minutes.
I realize that complaints like these sound like nitpicking and a failure of suspension-of-disbelief. Yup. But here's the thing: those only happen when the movie isn't good enough to get you past the issues. This movie is grandiose, overblown, and sloppy - among other things, the consequences of failure are essentially the destruction of civilization as we know it. Why is it always "go big or go home" on sequels? It manages some charming moments, but its simply not as elegant as the first solo Wonder Woman movie.
SPOILERS (stop reading etc.): I'm not done whinging about logic. WW can now make jets invisible. Again, it's a small thing and a throwback/tribute to older versions of WW, but ... was it necessary? It didn't really advance the plot. And by the end of the movie she can fly, pretty much exactly like Superman - and here we encounter one of those nasty little retconning problems: she couldn't fly in "Justice League," but she sure as hell could have used it. As for the Dreamstone and its effects: when Max Lord renounced his wish, that very nasty item would have reappeared. Diana would realize that and want to deal with it - but they didn't address that at all. And we never heard "Cheetah" renounce - it's implied she did, but she wasn't dependent on Max Lord (as almost everyone else was). Of course that may have been deliberate so she can remain a supervillain for WW to deal with later. My last item is actually more positive: while the appearance of Asteria in the mid-credits scene was ... improbable ... it was nice to see them slipping Lynda Carter into the story.