I feel like there wasn't enough information to properly explain how exactly the beast works. I am exceedingly curious because as we all know, pets and companions were removed due to the design constraint related to "The economy of actions" where having many minions unbalanced the game.
One concern I have is more leaning towards the druid. in 3.5 the druid was the predominant animal companion class and the ranger was merely a half druid. This felt silly as the ranger seemed like it should have a balanced way to have a full level pet, but animal companions ought to be a part of the druid as well. It would be disappointing to have to wait for a splat book for druids to have animal companion options.
Once there is a clear understanding of how pets are done, other sourcebooks could expand upon this idea for things like paladin/warlord/fighter squires or wizard/sorcerer familiars etc.