Mass Effect is the Star Wars of video games.
The things that made this game great:
-Storyline is fantastic.
-Being able to flexibly change the story depending on what decisions you make allows the game to have a maximum amount of fun.
-Character customization can allow you to make any character you want.
-Game play is fun, with some epic moments.
-Lots of side-quests and a large galaxy to explore.
-Voice acting is fantastic, there is a lot of it and the number of NPCs that you can talk to is insanely high.
-Most of the musical score adds to the experience.
The things that you may not care for all so much while playing Mass Effect:
-The PC version contains a few technical problems/glitches. The most notable one is the "Overheat bug" where if a weapon overheats, it will stay overheated until you reload your last saved game. It's a shame.
-A few of the character movements during cutscenes are a bit jerky and every once and a while a voice acting clip will have a small problem.
-Texture pop-ins when large or close up scenes suddenly appear on-screen.
-It's not easy to avoid sidequests that you'd rather not do. (Not necessarily a bad thing.)
-Most planets you cannot land on/survey.
-Story wasn't quite long enough for an RPG (to me.)
Mass Effect is a fantastic game and will absorb you into its well detailed atmosphere and immersive world. This game will make you love the Science Fiction genre if you don't already. You definitely need to buy this game if you own a decent enough PC, if you have an Xbox 360, you can always go for that version as well.