Okay I am going to reiterate what I said on my forum. And try not to get angry.
First off which version did you play?
Secondly, if it seems laggy it's because it is rendering a very large world, and as you travel farther it will render more.
Lastly, the greatest thing about this game is that it is a sandbox game, which are not very common nowadays, and most sandbox games aren't truly sandbox games. Minecraft is, for the first time in many years i can use my imagination again in a game.
As for the texture quality, no one nowadays cares about low graphics games, it's always about graphics for people and never gameplay and that drives me nuts. It's an 8Bit game, it's not going to get any better, and the modders who have looked into the game code have noted it as the nicest written Java they have seen in their lives making it easy and efficient for them to modify the game.
The point is, everyone playing seems to not realise that it's actually not a good game, sure it's okay, I mean when I played the free single player one it was okay but bored me after 5 minutes, and the fact that one person made it means nothing because it says on the website that there is a small team behind it now anyway. It seriously is not as good as people think.