I've enjoyed all three games. I think I played through the first one three times, the second twice, and now I'm on my second time for the third. Each one does tend to have that one bad feature. The first one's Mako driving can be a pain, especially if you spend the time driving around every planet. There is so much barren space between items to locate, and always a mountain range blocking you from going directly to an item. The second game has an awful scanning feature instead of planet exploration. So instead of landing on planets you control a slow moving reticule as it moves around an image of a planet. You get a bunch of probes and try to find the highest mineral resources. It's very tedious. The third game actually simplifies the planet scanning as there is only one item to get on each planet and the scanner points the way. However, you do have to locate which planets have items by scanning the area which can be interrupted by enemies but it's much faster than the old ways.
I know there are a ridiculous amounts of complaints about the ending but I didn't mind it. My Shepard had a choice of three ways to conclude the game and I've only seen the one I chose thus far. It's not a visual feast of cinematics, and you don't get to see what happens to everyone after your choice, nor is there any kind of medal ceremony. I guess that's what people want? It's more about giving you something to think about. Although Fallout 3 had a number of complaints with their ending, most games don't get this kind of press coverage over complaints. Maybe because the game is a RPG trilogy that provides many choices that impact the main character and the world? Though in most cases the choices really just lead to different dialog in later games I think, as the game often substitutes a new NPC in place of a major character that died in a previous game.
