The gameplay is basically what you'd expect from ME: three-person active squad moving through a (mostly) linear map and shooting things with the various loadouts determined at the beginning of the mission, and while you're there you might as well wander around the edges of the maps looking for things to "press Y to interact" with. These mission sequences are interspersed with exploration sequences where you wander around a map picking up quests (which usually but not always end up requiring a mission sequence) and finding hidden macguffins which you collect for your virtual office desk. And, between the cutscenes and the shooty bits, you have conversations with your squad to make them better at their jobs (and possibly have sex with you). If you're not a completionist, then you can probably plow through the main story in about 20 hours and therefore miss almost everything that makes this a Mass Effect game. You also probably won't like it very much. There's a fundamentally unpolished feeling to this game, that recons back to ME1 in some respects, but in other respects it feels almost Bethesda-esque in it's grandeloquent missteps and buggy nature.
And I'll tell you, at 20 hours in, I wasn't a big fan. It felt like a retread with a couple different aliens and the theory that if you liked ANY of the minigames in the previous series, then there would be at least one minigame in THIS game you'll like. Seriously: every gathering and exploring game from the previous series has a version in this game, and for good measure they threw in sudoku as an extra minigame because everyone likes sudoku, right? (Spoiler: not really.) The thing is, at 40 hours in, I was loving it. They were doing that "tell a big story while setting up a GIGANTIC story for the sequel(s)" thing that the BioWare team really excels at. It's fun, and I did end up enjoying it. But I missed the Wheel Of Morality, and I often felt as if the various options presented didn't really mean much, and didn't seem to affect the gameplay at all (which was quite disappointing -- I want there to be clear consequences when I make a decision, and that includes things like "this option is only available because you have 271 light-side points" and other examples. Much like Horizon: Zero Dawn, while there is a response wheel, the various choices seem to have absolutely no effect even on the specific conversation you're in at the time, let alone the bigger story arc.
Now, as the kind of person who won't leave a map or a corner or a building unexplored, this had plenty of that for me to pursue. But the maps themselves didn't feel particularly expansive, and while there were several of them, they didn't feel engaging in a way I was expecting from ME. And while the dialog was fun and the interactions with my crew clever, there weren't the deep and engaging interactions I've been led to expect from BioWare. And the writing was downright PAINFUL in some points ("pathfound" is NOT A WORD, GODDAMIT) which given the excellent writing of the Dragon Age and Mass Effect worlds was a real letdown.
Was it the Worst Game Evar? No, not by a long shot. In fact, compared to most of the other games on the market, it was pretty good; certainly miles beyond any of the Tom Clancy or Call of Duty games. But it didn't feel as engaging as other BioWare titles, and I wasn't as invested in the characters themselves (which is one thing that draws me to these titles). But it really does suffer in comparison to H:ZD, which was smaller both in scope and in reach but felt much more tightly put together and much more logically consistent within it's story.
So here's the thing: I think ME:A is money well spent, and a fun time. But I think had I played this game before I played Horizon:Zero Dawn, I'd like it more. It suffers immensely in the comparison, which is a shame, because ME:A is an excellent start. But it's BioWare, and with BioWare I expect something a little more... More. Which I suppose is unfair, really. Would I recommend this game to someone else? That's... a good question, actually. I'm not sure there were enough innovations and enough strong storytelling to suggest this game rather than suggesting someone play Mass Effect 1 instead (despite the intervening decade of development improvements). But I also can't say you should skip it; it's a fun ride, even if it's not brilliant. So, I guess my recommendation on ME:A is if you want something SF-ish and fun and light, then go for it. I have spend 100 hours on less-fun games, and at least ME:A feels like it's making those hours of play worthwhile.