While 1.1 may have added a new dimension to Terraria with the Hardmode addition. 1.2 took everything that 1.1 was and improved on it in every possible way. Countless new furniture, decoration items, and new backgrounds for every biome added. There is also the introduction of alternative ore and biomes. The Crimson alone greatly increases the re playability of Terraria by actually encouraging people to do more than one playthrough to experience everything the game has to offer. There's also the ability to better customize your character to your own taste with dye and vanity accessories. More than just making an already great game and making it x10 greater, it represented a revival of Terraria after development ceased for a time on Terraria after 1.1
1.3 will be awesome indeed. Based on what we know, we don't know how much 1.3 will change the game compared to the other updates and my opinion may change. Still 1.2 makes the game feel very new even if you had played 1.1 beforehand. 1.3 seems to aim more about perfecting what is already in the game and adding Expert Mode for veterans and players who love challenging high difficulties.