Use left trigger to pick up animals. Right trigger to attack, witch can also be used on a picked up enemy's. pull left stick back to decelerate and forward on the stick to accelerate. The jump button is used to land and fly.
While slower than a ptera, they're pretty useful. They can pick up more dinosaurs and can kill them while flying, allowing you to pick off raptors and sabres and other small horrors with relative safety. Keep an eye on their stamina, just like a ptera you don't want to be forced down into a death trap
Getting a massive TLC update in March 2018. The saddle will act as a mobile smithy, Argentavis will be able to carry with Talons as well as with its beak, reduced carry weight on obsidian and a few other unannounced resources (similar to the mammoth and wood), and will also gain a Rapid HP Regen upon eating (likely from devouring corpses and not specifically food from inventory). Like so people can see!