Achievements are really nice if its for games that you are renting or borrowing. They encourage you to get the most out of the game before you return it. Thats what i use to do a couple years ago. Rent the game, finish it, get all the achievement, and return it for the next game.I had a lot of fun with games that i would have never thought of buying. The achievements are proof of my experience. I don't really do that for games i buy, since i have all the time in the world to finish them.