Whited-out for your convenience
This is a perspective of Mass Effect from someone who hadn't previously played any of the games and wasn't effected by the controversy in March.
My most favorite game from the Trilogy was the first. Playing on the X-Box, I was subjected to the horrible frame-rate so I tolerated the combat at that point. Playing the second game allowed me to appreciate the combat, changes and all, ultimately though Mass Effect 3 nailed-it. I missed my big numbers on my armor/guns in the other two games, 2 and 3 felt less like an RPG to me and more of games molded by their action.
I enjoyed the music more than anything else in the series, Jack Wall did an amazing job with the first two games. It is telling to me, of quality, that the Menu music for the first game isn't named anything, isn't included in the OST and yet is one of the best pieces. That song is used to amazing effect in 2 and 3 and serves to make emotional scenes even more poignant. I can't speak very highly of the third game's generic remixes of his work...
I dis-liked the storyline involving the kid; I was playing a Renegade and it contradicted my character. The ending didn't engulf me with rage, despite the internet's influence over me, I didn't feel angry I just found the re-colouring of that explosion lazy. The A, B or C 'ending-machine' I can forgive, I let that slide for Human Revolution. The kid stuff pays-off but, again, my character wouldn't be too scarred by what happened to the real-live (or dead) person. The 'Star Gazer' and his, grandson(?), came across hokey if only due to the Giant Bomb's regurgitation of the phrase over the past year.
I have a suspicion the ending would have left me wanting without the Leviathan DLC. The game seems to have the same problem as Assassin's Creed 3; it doesn't want to indulge the player with answers, it'd rather have them fill in the blanks, or sell you the answers at a later date. (It's seems to be more of the former)
Having to shoot some of my team-mates in three was hardcore but that's how I chose to play. I would liken shooting Urdnot to killing the Boss in Metal Gear Solid 3, just much worse, at least Kojima only made me shoot her once, this game made me commit to my decision and hit that Right Trigger, a further, two times. The third game in general made me depressed, shit was heavy. Being me, I accepted every side-mission and sometimes the game felt like a chore to me, however, considering how lost I felt after finishing the franchise I would say the game affected me more than I had realised.
Cerberus. You work for them in two, they justify themselves as doing what's necessary and claim that most rumors about their organisation aren't true, although in three they are the most evil motherfuckers who ever lived? That's out of left-field. To be fair, this is touched-upon, shortly by Illusive Man's psychology; trying to sucker Shepard in with personalities she'd feel sympathetic towards... still a bit silly. Evil might be the wrong word, after all, the Illusive Man seems to have the right idea at the denouement, I still elected to destroy the Reapers, it's what we came to do. Also, his goddamn face, who'd trust anything he was saying at that point?!
Space isn't necessarily my thing and whilst I liked watching the occasional Next Generation episode as an adolescent, I don't want to commit to buying the Blu-Ray releases. I find myself playing a number of games that have genres that wouldn't fly with me in other media, maybe i'm easily bored and the promise of interaction makes me pay more attention. Video games do tend to follow a certain structure; watch a cinematic then fight some hordes, I find that more my pace than to just sit back for 2-3 hours.
In closing, I need to elucidate, the series is fantastic and in writing this wall of text you should know I really like it. I do not give this treatment to every game I play. I felt like I needed to experience these games that I knew little about, they were held in such high-regards and they deserve it.
Will edit later to make less disjointed.