Niantic and The Pokemon Company International are about to update Pokémon Go with some much needed enhanced augmented reality features. The "AR+" feature will be available exclusively for iOS devices that are running iOS 11 or newer and iPhone 6s devices or newer.

To those playing on unsupported iOS devices or Android devices, you can kindly shove off. That's the gist of what I'm seeing here at least.
After activating the new AR+ feature in encounter mode, individual Pokémon will be more accurately positioned based on their surroundings and environment thanks to the six degrees of freedom the technology provides. By utilising ARKit’s advanced 3D AR scaling, a Pokémon’s size will be more accurately based on the world around them, changing in perspective and size as Trainers move closer or further away.

AR+ mode also adds new dynamic gameplay to Pokémon GO encounters that will provide Trainers with more ways to catch Pokémon. Trainers can now get closer to a Pokémon to receive a special capture bonus, but Pokémon are aware of the physical proximity of Trainers, so they must approach carefully as they may flee if a person comes too close too quickly. Getting closer to a Pokémon using AR+ has unique gameplay benefits, including being awarded the new Expert Handler bonus, which provides more XP and Stardust.

That all sounds very, very cool. If you'd like to see a small snippet of the AR+ in action, All Games Delta has a short video showing it off.