Vers (Brie Larson, but you should know that by now) is a great warrior of the Kree race, on the frontline of the war against the Skrull. She's earnest but prone to fits of emotion, and good lord does her squad commander, (who happens to be Jude Law) not approve of that. Unfortunately, that doesn't reduce the necessity of them working together, when a Kree spy deep in Skrull territory needs rescuing. And helpfully Vers has ultimate cosmic plasma-y powers, making her an excellent weapon.
A shame then, that an ambush throws her into Skrull hands, hands that are entirely too keen to dig through her memory for secret knowledge of Kree technology, and a mysterious spaceship back on Earth, which Vers, as a Kree warrior, seems to know an awful lot about.
Given that the trailers give half of this away, I don't think it's much of a spoiler to point out that Vers spent quite a lot of time on Earth in the backstory of the film, and that she ends up there again as the war continues. This is also where young Coulson and Fury come in, both of whom are rather less experienced with aliens back in the olde worlde of 1995. (Good lord I feel old.)
Akin to Guardians, that makes this one of those odd period pieces, where the filmakers are throwing in cultural touchstones, but with a slightly lighter touch this time round. I think that's a good move, as there's potentially a lot of things going on here, and pushing that level of nostalgia in on top might have been difficult.
Partly it's a prequel, effectively to the entire MCU, and to an extent that feels like a weakness. I don't know if that's my own personal superhero fatigue (there have now been 21 MCU films), but there are a few elements that pop up that you can see coming a mile off, because they have to be present for future (previous) films.
Larson as Vers is definitely a high point in it, with the film avoiding a lot of the "origin story" traps that we've seen in similar ones, and starting out with her as a fixed figure. Obviously the film has a few revelations, but it's building nuance onto an already strong personality, rather than going through a full build cycle. It also allows her to flip the usual dynamic and recruit Fury as the hapless sidekick, which I suspect he had a lot of fun playing.
There's also fun with Goose the cat, who apparently Skrulls are scared of. (There's way more there in the backstory, but I will never tire of Fury cowering behind a moggy.)
It's solid, and it's got a reasonable arc in it, but I suspect there's less and less in the MCU well that they can dig out for new films that will really surprise me. (I mean I'm almost certainly wrong there. I will undoubtedly keep watching anything they put out. I just think 21 might have been enough. If they decided to just stop after Endgame - they won't - wouldn't be that worried.)
Anyway, this one is decent, but going by the takings, you've likely already watched it.