For example, I'm using Debian, and I think we could learn a thing or two from Mint about how to make it "friendlier" for new users. I often see Mint recommended to new users, but rarely Debian, which has a goal to be "the universal operating system".
I also think we could learn website design from.. looks at notes ..everyone else.
Its releases are so far apart that the default installer stops working in between releases cause it can't handle the changes to the repos.
Its default software selection is outdated, makes no sense (multiple tools for the same task), and is grouped illogically. If I want to run Xfce, I shouldn't have to install the KDE group to satisfy necessary dependencies. If I install the base group, all dependencies for using the package manager should be satisified. And Libreoffice shouldn't be installable only via an unofficial, unsupported third party repo.
"Some modern computers have started to offer motherboards that use Unified Extensible Firmware Interface (UEFI) as a replacement for the traditional BIOS."