According to Atari, "The game features the most accurate horse models and animations yet realized in a video game," which means that it'll give Oblivion a run for it's money. But does it have horse armor? Doubtful. But it might feature some mane-brushing minigames, so you won't be missing it.
According to Atari Senior Product Manager Emily Anadu, "We are looking forward to providing the horse-enthusiast community with a rich and authentic game that allows gamers to take care of and compete in a variety of challenges with their horse." So if you've always promised a pony to someone in your family, the cost (and cleanup) will get a heck of a lot cheaper this fall.