State of the game is not that great, player numbers are dwindling and unfortunately game disappointed many. One thing to know though, Relic Entertainment didn't stop working on the game and ever since game launched we had several updates. Updates before this free DLC included annihilation mode which wasn't available in the base game. They also scrapped the ingame currency which was needed for players to unlock Elite units and Doctrines, now everything is available from the start. They also added several new maps and introduced a lot of balance changes, game already feels way different than it did on launch.
Endless War DLC includes three new Elite Units that are quite fun to use and they add another strategic layer to the game, and of course they look cool too as you can expect from Relic Entertainment. Space Marines received long time coming Ironclad Dreadnought, very cool crowd control tank unit. Orks received Lifta-Droppa, crowd control and decent dmg unit. Eldar received Wraithseer Kayduin, very strong walker unit. If you haven't read my review of the base game you can check it out here. Game has a long way to go to redeem itself, with new expansion and several new races who knows, Relic might make Dawn of War great again.