Dragonlord's Servant being only a two-drop creature, however, is quite relevant. Making your five-drop Dragons, which many are, cost only 4 mana is extremely good. The Dragonlords costing five total mana instead of six is also very relevant. Having a 1/3 body lower on the mana curve is also helpful so that if you're focusing on Dragons, you have more of a board presence in the early game. True, cards like this will draw removal, as well, which can actually be an advantage as it's removal that won't come later.
In Commander, where Dragons are absolutely flooding the format, this is going to be a handy complement to the aforementioned Dragonspeaker Shaman. Imagine having your Stormbreath Dragon cost only two Red mana to cast. Suddenly, your six and seven mana Dragons become even more cast-able. Dragons of Tarkir was going to be all about the Dragons and here's just another way to make them even scarier on a Constructed level.