Its.... kinda okay game? I guess? The game is split into two awkward halves, the first is deckbuilder/tactics game that mostly work well cause its firaxis and they know their stuff. Except its way too long and repetitive.
The reason its so long is because of the second half, a weird pseudo Marvel dating game. Between every mission you go back to a campus with ever Marvel hero and you just chill there with them, you can go and do outdoor paint with Wolverine (shit you not) while the world is literally about to collapse. First, you gotta be an hardcore Marvel fan to enjoy this part cause most of the character are at a point where they all finish they're traditional arc and they don't really grow, its just hanging out with them (with some dating sim throw in). Your actually character has essentially zero personality because he/she a nameless character you make, so they never develop any chemistry with any of them, its mostly just the hero alternating between reiterating their basic story and lavishing praise on the main character.
I have to disagree with you about being a hardcore Marvel fan, I wouldn't consider myself one, I know the characters obviously, but I have pretty much ignored much of the cinematic universe. But I really liked this game, I liked trudging around the open world part of the game exploring, figuring out the puzzles and taking in the lore.
However, I do have to agree with you, there is a lack of urgency in what you're doing, especially as the game ramps up towards the end. The world is ending but you're only allowed to go out and beat up the bad guys once a day. It can't be that bad now can it, most laid back apocalypse ever.
Its a shame the game will never get a sequel, especially as it ends on cliffhanger. I think a sequel probably could of ironed out some of the wrinkles and made it a better experience.
But if you can get this game for free, I'd recommend it.