Getting back to the title at hand, I don't think I will be very wrong if I say that as far as "world-crafting" goes, Mass Effect is more or less a pale copy of Star Wars.
Wait. Hear me out here first.
There is a difference between telling a story and creating a setting, the characters and the unique abilities that people will identify them by.
As far as the design of the world itself, BioWare showed very little in the way of imagination. The game puts you in the role of a human commander tasked with saving the galaxy from an ancient threat. There is the Galactic Council and the issue of various humanoid and less humanoid alien species interacting in social, political and other ways with humans. You play as a Spectre, an elite galactic unit acting under the orders of the Council (Jedi Council anyone?), yet autonomous enough to decide the means of going about achieving your goals. Should you choose to play, say, a Vanguard class (like I did), a number of Biotic abilities will become available to you, some of which (like the Throw and Lift) will function strikingly similar to Force powers.
All this, minus the light sabers, more distinct and imaginative characters and locales, which is what made Star Wars such an incredible hit over the decades.
On the other hand, the story itself is classic BioWare work and in a very good sense too. The very ideas behind the events in the game, the way that the characters interact and the more mature moral choices than we've ever seen in Knights of the Old Republic, make Mass Effect a true delight to play. The lack of more originality in the design of the world is definitely more than compensated by an intriguing storyline which even presents some very interesting philosophical issues. I'd discuss those with you here, but I'm inclined not to spoil the surprise for you.