I love it!!!
There isn't much to say about the game because its still in alpha but i'll say it is fun, addicting , relaxing, slightly creepy, and sometimes wacky
The base of the game now is just play around with the block types and try to get diamond and thrive rather than just survive. Not to say that the game is not a challenge; There are exploding failed attempts at a pig model (and yes i know that that is what creepers are for a fact I heard it from notch), skeleton archers, giant spiders, and zombies (the slow kind).
There is some technique required for quick and efficient mining, like always dig in layers never dig straight down unless you want to burn up in a pool of lava, and use the weaker materials to dig away stone and stronger ones to dig away thing like coal, iron and other materials that require better tools to collect.
I honestly don't have much else to say about the game other than its fun and you should get it now while its half off only for alpha cause beta is rapidly approaching. If you don't want to spend money on it at least play creative mode that is free to let notch know that his work is appreciated.