What’s bad about Linux?

Incomplete or sometimes missing regression testing in the Linux kernel (and, alas, in other Open Source software too) leading to a situation when new kernels may become totally unusable for some hardware configurations (software suspend doesn’t work, crashes, unable to boot, networking problems, video tearing, etc.)

Why is Linux so unfriendly?

The main reason people still perceive Linux as unfriendly is because most people have lived their whole life running Windows and/or some version of MacOS, and probably did so on prebuilt computers. All they did was sit down and go. After a while, you get used to the look and feel, and how it works.