I think I got a different pleasure out of Mass Effect than what critics of the sequels (or fans of the original, if you prefer) did.
I didn't especially care too much about the hows and whys of the plot or universe. I never read the Codex, except if there was a plot point I was really struggling to understand or a reference I didn't get. I found a lot of the lore to be pretty generic sci-fi ripped from Star Trek. There's the long-lived democratic race (Vulcans to Asari), the angry warrior race with a genetic defect (Klingons to Krogan), the cyborg enemy that forcibly converts its victims (Borg to Reapers with a bit of Alien thrown in at the end), warp drive (Mass Effect engines), so on. Beyond the specific words used, there's little that's truly unique about the Mass Effect universe.
I liked the characters. I liked finding out a little bit more of their history after every mission. I liked learning about their homeworld and their personal struggles. I liked Joker's growing relationship with EDI through 2 and 3. I loved Liara asking for your input about her histories of you. I loved Tali's anxiety about her pilgrimage and Garrus' dark times on Omega. I remember Kaidan's confrontation with Shepard on Horizon a lot better than I remember that mission itself. I liked ME2 so much better than 1 because it's almost all character introductions; most of the main quests are building up a rogue's gallery of interesting new characters, and then you get to interact with them even more for the loyalty missions.
I loved 3 in particular so much because it gave my Shepard a personal conflict that I felt was lacking in a game where I could decide that Shepard's personality changed at the drop of a hat. The dream sequences, her reaction to the [spoilers] on Thessia, having to reassure her crew as the outlook only gets more grim; these are the reasons I played Mass Effect. I didn't care if the ending was exactly as bad as everyone said it was, because I got to see Tali getting wasted in the Normandy's galley and Garrus and Vega trading tall tales in the crew lounge. Those are the moments I take away from ME3 and the series as a whole, and they're enjoyable to me.