A heavy criticism of a lot of these ubuntu-based distros is "ubuntu + a custom PPA", but system76 does actually put in a lot of work into a custom kernel and some neat UI tweaks that make the OS on their hardware really well. They also have a firmware updater for their systems built into the settings program. The whole experience is a lot more refined than Ubuntu, I believe. It's a great OS for their machines, as well as any laptop with hybrid Intel/Nvidia graphics.