First of all you can try Linux yourself, just install a Virtual Machine software and try some different Linuxs to see what's all the fuss about. Or if you have an extra drive or partition dual boot.

What can I expect to find as a casual observer?

I started as a casual observer, dual booted for a long while, but the more time I spent on Linux the more Windows problems became glaringly obvious. But there's one major trap that a lot of people fall into, which is thinking Linux is just like Windows, if you try to do the things the Windows way you're going to have a bad time, and this goes for everything from installing software to changing configs.

Why does Linux do that's "better" than Windows?

There are a lot of objective but technical answers to that question, from the scheduler to memory management, but I think that for the most part most people don't care that their system occupies double the amount of RAM when idle because they have the ram to spare anyways, so I'm going to talk about things that I (somewhat) subjectively think are better and why.

• Package managers: in Linux you install things through a package manager, similar to how on Android you use the Play store. The reasons are similar, e.g. more security, updates cover the entire system and easier to find software. To download an executable and install it manually in Linux sounds just as absurd as downloading an APK and installing it manually in android.

• YOU are in control: Linux is the only one of the main 3 desktop OS to allow you FULL control of your system. Don't believe me? Try to uninstall the file explorer from Windows.

• Customisable: Windows is NOT customisable despite what you think, in short you can change your wallpaper and that's it, in Linux you can change ANYTHING, from the program you use to browse files to the backed you use to draw graphics, it's a whole new level that windows simply can't match. I think someone who mods their games would be very interested in modding their OS, and Linux will allow you that to a level you didn't knew possible.

• Peripherals support: yes, most hardware is built with windows in mind so their programs are built for windows, so when you plug something new you need to wait the 5 min until windows discovered what it is, then wait until it installs the drivers, then probably install a third party driver or app companion. Linux on the other hand uses a monolithic kernel, this means that the Linux Kernel contains drivers for all the things it thinks you might want to plug in, which results in the absolute majority of things working out of the box immediately after plugging them in. On rare occasions (e.g. NVIDIA cards if you want the best performance) you need to install third party drivers, but in general things just work. This means that Linux supports hardware even though the hardware doesn't support Linux, which is not the case on Windows, the best example I can think is PlayStation controllers, since they're not meant to be plugged on PCs they don't work on Windows, but they work out of the box on Linux.

It's not all roses though, most software is made for Windows (game included) so you need to run an "emulator" (not really an emulator, but easier to understand) to be able to use them. The name of this "emulator" is WINE (which means WINE Is Not an Emulator), then there's Proton which is a compilation of WINE and other libraries that runs from steam to let you run games that are not native.