Minecraft: What do you think?

Howdy everyone :)
So, technology also includes the fun stuff like online gaming. A couple weeks ago, I went over to Ramsey Elementary for their SummerPlus program. One of the guys was talking to me about games, and he said that Minecraft is incredibly fun. From what I've seen, Minecraft allows you to mine things from your surrounding, and then use them to build structures. Why? I haven't seen it yet, but supposedly there are monsters that show up at night, and shelters help you defeat them. If you're into interacting with your game's world, this one sounds like fun. Their is a beta version that you can purchase, but there is also an older version that is free to play.
Check it out and let me know what you think.
http://www.minecraft.net/