I have played both this and Minecraft, both games are as someone above said are good little time wasters. But both games are drastically different when game play comes into question. Minecraft is mainly about building and well obtaining resources. Terraria, while possessing some of those factors is more about the exploration and cooperative play. Some of the boss fights in it are extremely difficult and cannot be tackled with a single player. Though Terraria's battle system maybe slightly clunky, as of now the over all game is far more developed than minecraft, as well as incorporates RPG elements, such as magic. It also gives you far more options crafting wise, and item wise.
That all being said, both games aren't that much fun to play alone in. The biggest problem with minecraft is it's buggy coding, and multi-player is a pain to deal with unless you have an excellent computer, and even then servers tend to lag terribly. Terraria's multi-player is far superior.
Not my favorite games, but I sure as hell wouldn't rule them out either. They have provided a lot of fun for me, but I only play when my friends do. Haha. *shrugs*
I just get slightly peeved when people compare Terraria to Minecraft, though similar, they are two completely different games.
