I find the branding of the gigantic P and the exclamation point, when used as a backdrop, to be excessively distracting from the content in the foreground.
To be fair, they market themselves as "Pop!_OS is an operating system for STEM and creative professionals who use their computer as a tool to discover and create." on the main page for the OS.
I'll admit, I don't love the !_ but for the opposite reason - it feels faux techy to me.