Mass Effect 2 is vastly more fine-tuned and polished than it's predecessor. I think everyone has that same experience when playing a later iteration of a series and seeing how the same game-play mechanics and concepts are presented in a slightly more primitive light. Such is the same with films. For example comparing Star Wars: Revenge of the Sith to the original 1977 Star Wars, visually there's no contest between the two. However, that doesn't factor narrative, and characters, and everything else that makes films great. On the surface, Mass Effect 2 is an infinitely better game. However, I felt that the first Mass Effect had a better storyline with more shocking moments and plot twists. That's not to say one is a better game, but Garrus's ineptitude in battle and some of the less polished aspects of the game's mechanics aren't the only things to consider when judging the merit of our medium.
On another note, given that I mentioned films and want to bring up another form of media, literature (that is to say novels, graphic novels, short stories, and poetry) ages very well. Outside of the evolution of human dialect, excellent books transend time like no other form of media.