Some players feel that hunting for achievements 'kills' the game or forces them to play in a way they don't like. In my opinion, the most important thing about gaming is that you're enjoying yourself.  Achievements offer a fun way to track your progress and introduce you to challenges you'd never consider otherwise (like dragging a garden gnome all the way through Half Life 2!). Play to enjoy the game first and foremost, but if you're hungry for more, Achievements are the perfect way to get it!