Firelands is one of the most cohesive and engaging locales Blizzard's team has brought to life, in my opinion. Much like Deepholm and Vashj'ir, the Firelands exists to bring the realm of fire to life, when the daunting Sulfuron Keep only existed in our imaginations prior. An interesting piece of info was that Ragnaros' model was rebuilt from scratch, completely overhauling his skeleton, animations, and feel. The new Ragnaros is one of those things, to me, that the Cataclysm did right -- create a new thing with the heart and soul of the original. Ragnaros looks like he belongs.
Check out the full interview after the jump.