I was brought to Terraria because I had heard it was like Minecraft, and, being an avid Minecrafter I decided to give it a try.What I unearthed was a completely new, and in some aspects better experience. Sure, it gave a nod to Minecraft in the fact that you can place and destroy blocks. But, that is where their similarities end. This is a completely different indie game (hence the word "indie") and its diversity can make it appeal to many people, perhaps even people who aren't interested in Minecraft.
If I had to make a comparison here, I would say that Terraria is a cross between Castlevania and 16-bit Zelda, with, sure, a little bit of Minecraft action thrown in there. The game has no real storyline; you gather resources, make a house and go mining in the seemingly endless underground. There is a myriad of bosses out there, and plenty of remarkable biomes. An interesting aspect of this game that I have found is the help that it gives you at the start of the game; you spawn in your world right next to an NPC that gives you advice and can show you any crafting recipe. This makes basic crafting far less hard than it could have been, and once you gather different resources you will start to realize how sprawling the crafting system really is.
However, although the crafting system is fantastic, another even more interesting aspect of the game is its multiplayer. You can play your world in single player, but whenever you log onto a server, your gear stays with you. This is a great way for people to go pvp on the fly without having to build up all their resources on that server.
All told, I have spent around 15 hours on this game. I have gotten about halfway through (a third if you are a perfectionist) and Terraria keeps me coming back for more. It has a fantastic wiki, and plenty of stuff for the fans too. Add that to the extremely agreeable price of $10, and you have a very solid game.