While I can't say if the game is better or worse than what it was in Alpha, I can say I had a much more enjoyable experience back in the Alpha days. Maybe that could be chalked up to nostalgia, but personally, I think it was because how the game was more or less a mystery to us. Digging out that first diamond was something to remember, the fear of the dark was bigger, the threat of dying made sure you knew where your house was if you died, digging out a hole in the wall to look for coal was the ideal way to spend the first night, dungeons seemed like an impossible task, and so on so forth.
Nowadays? We know all the little details of the game, and the ideal way of going about our survival. Charcoal and beds have diminished the threat of night, and we know the ideal way of finding diamonds. The difficulty doesn't scale well, and the mobs require additional bonus's in order to be threatening. Stacking foods has made it easier to recover health, and potions give you an inmate advantage over the rest of the game, and other players, if in a multiplayer server. People use mods to try and replicate the feeling of the unknown, but with not all too much success, depending on the user and the mod.
This is all my opinion, and your free to your own, but this is really the main reason I can't find that much enjoyment in Minecraft anymore.