The recess is in between the hinges along the bottom edge of the display to more safely secure the pen when traveling or not in use. The approach allows for a full-size active stylus that can offer a better and more comfortable grip when compared to most Lenovo or tablet pens.
https://www.notebookcheck.net/Dell-Inspiron-13-7390-and-7590-2-in-1-have-magnetic-pen-garages-for-housing-the-stylus.422319.0.html
$1,500 is the highest of the high end, premium ultrabook's price tag.
For mid range laptop comparison,
Dell Inspiron 7000: $1,400+, heavy, no Thunderbolt 3, extremely poor battery life, poor dGPU
Lenovo Yoga 700: $800+, light, yes Thunderbolt 3, better battery life, much better dGPU
I'll take Yoga's soundbar hinge + Surface / EliteBook's magnetic pen attachment any day over this "pen garage".
Also not including IR facial recognition on any 2 in 1 laptop is a deal breaker in 2019.