The Mako was bad and you should feel bad for liking it. ME1 was a technical mess (doubly so prior to the PC version) with horrid shooting and mediocre RPG elements that had minimal actual depth, but was bogged down with tiny, irrelevant stat changes. The inventory was atrocious, the endless slightly-improved-items were terrible and the horrid cut-and-paste sidequest design was downright deplorable. Any and all "sense of exploration" was ruined when all the sidequests were composed of the same obviously reused assets accompanied by a brief text description that would come up on the screen, all taking place on Anonymous Ludicrously Mountainous Planet With A Slightly Different Skybox Number 26.
Oft times the boss fights were so janky it's surprising that it came out of Canada and not Eastern Europe, and they were universally badly designed and implemented. The final boss fight against Saren in particular is the worst boss fight in the whole series, because while the ME2 final boss was "silly", this final boss is the complete opposite of fun. It's a re-skinned Geth Stalker, jumping from rooftop to rooftop like shitty spiderman cosplay, spamming powerful abilities at you. The "challenge" of the fight comes from the fact that somebody plugged in a ludicrously high HP value for him, so instead of the usual frustration of a geth stalker/sapper fight, which would be over in under 15 seconds, upon which time it had already outstayed its welcome, this fight drags on for like 5-10 incredibly frustrating minutes.
The lauded story and dialogue aren't even that good. The story has plot holes and continuity fuckups within itself. A few of the characters are strong, which is probably the nicest thing I can say about this game. ME1 is a classic example of a developer's overextending themselves, trying to do too many things and failing at most of them as a result. It doesn't just have bad design choices, it also has bad implementation of those choices, with technical problems on top of all that. The game sells you on promises of an epic space opera mystery that you will get to personally shape, but everybody should have known that almost all of your choices would be trivialized. ME1 doesn't get flak for this because the choices weren't required to bare fruit at this stage, but squandered potential doesn't win a game any points in my book. I don't think people like Mass Effect. I think people like the idea of Mass Effect, and look past its numerous obvious problems because of that. All of those promises that were inevitably going to go unfulfilled. But that's not something I can support. I would go as far as to say that ME1 is a bad game, with more things it does wrong than things it does right. I do not say this as somebody who has not played it - I actually finished the game more than five times so as to explore the different possibilities, the different classes and so on. I know the game like the back of my hand, but after all was said and done, I can't say I like it.