I started playing around Beta 1.2 I miss the days when I was still discovering everything, learning to craft, not knowing what all the different mobs looked like or did. The game seemed so much bigger then, so much more to discover.
Looking at the big picture, however, I love all the features added when the game was released in 1.0. The game feels more like a video game now, it's more complete. While it's still a sandbox game, there is now an objective (sort of).
While the game will never be the same as it was that first week playing it, I think my favorite version of Minecraft is the current one.