I just recently picked up MineCraft, and though I absolutely have not gotten through all of the content, I'll just make a few comments. First, MineCraft is great. When you look at it objectively though, it's mostly a time-sink. Much of it's greatness comes through with your imagination of what you can create next, or what the game will let you create next. Is the game worth 8 million dollars though (If I were a publisher, or basing the game's total value objectively;outside of just marketing.)? No. Personally, from the $30 I spent on two accounts (which is for multiplayer only -- one was for my brother) when considering the Classic game is free, was not worth it. I mean the multiplayer concept is fluid and can really make the game for some people... but to me some of that subjective creative energy I can pour out in it is lost on that. That and the fact that when we got it, damage was turned off, and part of the reason I wanted multiplayer was so that I could guide my brother out of "peaceful" mode. Now it's in, but bows don't work, so despite building two, I can't kill an explosive zombie. One last comment about the actual game, the beginning game content seems immense, but end-game content rather sparse. I think there should be more effort being put into almost each and every (okay, a little bit overkill) combination being given a craft creation.
Outside of the value I give it, there are some things that are bothering me about Notch. Does he seem like a good guy who created an incredible game single-handedly? Yes. But I get a very John Romero-esque feeling about his plans for a future studio and the investments he plans with those multi-million. One thing that startles me currently is that he has a link to (unofficial) tech support, which does a lot of work for him I'm sure, but guess what? The tech support asks for donations as it appears that Notch doesn't pay him. Even if the guy does it on a volunteer basis, I think Notch should still pay him out of the recesses in his heart (or substantial wallet). That and he should really have a larger staff with him by now, as I'm sure the Beta would be out otherwise (as it's just bug fixes to match the quality of "Classic").
A niggling point that I'm sure developers would take offence to, is that I think he should really drop the price-point. At the very least, set himself some arbitrary limit of profit so that he it can be more open. With him still working on it. I know that sounds like charity, but if you considered this guy's game a salary, companies like Activision and EA could do no wrong.