Pro Pop! makes GNOME look really good
If you're a fan of flat desktop interfaces reminiscent of Material design on Android, you'll like the theme that comes as a default in Pop! OS. The desktop and title bars all use a bright turquoise theme that makes the interface feel happy and borderline retro-chic. It's like something you'd find printed on a ringer t-shirt.
Pro Made by a hardware seller
System76 is a hardware company. It configures machines to ship with Linux pre-installed. This means its entire business model centers around delivering a quality desktop Linux experience.
As a result, the company pours more attention onto the desktop. It can fix visual issues and may be able to provide a smoother overall experience than you would have installing a different version of Linux on your machine yourself. Providing Pop!_OS also empowers System76 to make certain fixes for users directly rather than having to coordinate with Canonical or the broader Ubuntu community.
Pro A separate NVIDIA version
Most linux distros seem to hate Nvidia's graphics cards e.g. Fedora and OpenSUSE. System76 have decided to be kind. They have decided to form a good relationship with Nvidia fans and Nvidia itself. By creating a separate installation media that is dedicated for providing support to Nvidia's graphics cards. Even going as far as putting Nvidia's driver updates on Pop!_Shop for users to easily access and install.
Con Includes too many unnecessary programs
For a distro targeted towards devs and engineers, there is a little too much bloatware. Geary, Firefox, GNOME Calendar, and others are fine applications, the target audience should have no problem installing these if they need/want them. There is even an included app store like UI to do this!