It's more than that; you also get to build scructures with as much flexability as lego, explore a randomly generated world that sometimes produces amazingly beutiful scenery, figure out how to build complicated systems from small trivial components and top it all off with the random-interval reward system of mining.
Minecraft hits so many of my "god I love this game!" features it's easily my favorite game of 2010, even though it was an alpha release.
Minecraft is not an FPS, neither does it have elements to it that are similar to Farmville's. Go try out Minecraft and come back when you're more informed on the subject.
While Minecraft may be in first person and let the user use an bow-and-arrow as a weapon, calling it an FPS is distorting what the game really is. Shooting is a feature of it, but it is not what the game is known for.