For many folks the hardest part of installing linux is getting past the UEFI boot loader in modern BIOS. This is unrelated to linux, and more related to either 1) Microsofts continued desire to rule and regulate every breath you take by "influencing" systems and motherboard manufacturers OR 2) a genuine desire to enhance system security. It's not always easy to change the BIOS settings to allow booting anything other than the manufacturers installed OS.
Once past getting the system to boot from either the DVD drive or a USB device installation is pretty quick and usually painless. Dual boot or replacing windows is up to you.
Once up and running, most desktops are similar to what folks are already used to, with menu entries logically grouped usually. I would say going from Windows to Linux desktops is about as much of a change as going from Windows 7 with the traditional desktop to Windows 10. A pain in the butt now and then, occasional internet searches to figure out where something is that isn't where it used to be, same old same old, just like new versions of windows. If you choose some oddball distribution for your first experiment with linux, you are making a poor choice. Stick to one of the mainstream distributions. I like linux mint, standard Ubuntu is good. If you choose the Kazakhstan Hannah Montana build with the Futurama desktop in special edition dark grey on black theme have fun, let us know how it works out for you...
My new Toyota Tacoma is very different from my 2000 Tacoma, which was very different from my 1985 Toyota base model pickup. Some fumbling to find controls, some grousing about things that are or at least seem stupid. Pedals and steering wheel are still in the same places at least
To blow out a few old truths that are no longer true:
1) Linux doesn't work with most hardware. BS. Scanners can be a bit odd to set up although the Japanese Epson and Canon sites often have linux native applications in English, they just aren't on the US sites. Anyone smell the stench of microslop? Lightweight desktops and file managers don't always handle automounting removable storage well. This is only something I've run into when trying to keep utterly obsolete computers somewhat useful or oddly enough with the current builds of Ubuntu Studio - which uses the lightweight xfce desktop. Never have issues with linux mint and removable storage. I hated xfce the first time I ever had to use it, can't say it's gotten much better over time. Not everything in the linux world is sweetness and light.
1a) Video - Most video cards are reasonably to excellently supported under linux. If you have a strict only open source on my machine, no proprietary drivers allowed view you will still be able to use decent hardware, but may not get the optimal possible results. After doing the initial installation, you may need or want to install the video card manufacturers driver set. This may appear in the drivers part of your settings panel, or in linux mint there is a system checkup that will advise you the drivers are available, recommend which is the best option for the machine, and give you the option of installing it. Usually a reboot is required after installation. You may need to right click on the open area of the desktop to select your desired resolution and optionally change font sizes and icon sizes. This is particularly true if using a 4K monitor. Just as I had to make these changes on my windows machines, I've had to make them on linux machines. Icons and fonts were just too small on a 4K display. Not anything really different from Windows with updating drivers, there just are a lot less driver updates needed. To be fair, Windows 10 has greatly reduced the need to manually install all sorts of drivers, on that front at least they have taken a lesson from the linux world.
2) Linux sucks for gaming. Yup, got to say this is correct in comparison to gaming consoles, where most gaming is done these days. Steam and a few others allow quite a lot of games to run on linux, but odds are it's wrong for you if gaming is a major requirement. So is windows in many cases though, seems xBox and PSx consoles rule, with nVidia Shield bringing up the last of the top three. Windows PC gaming is still more flexible than linux. Both linux and Windows share the pain of ridiculously inflated video card prices, neither one can get you past that mess.
3) You have to use the command line to do anything. Once upon a time this was true, just as it was in the days of PC-DOS and MS-DOS. In both windows and linux access to a command prompt is sometimes required, in other cases it may let you do things quicker or more efficiently. I use linux everyday and seldom need to open a terminal. Don't be surprised to see command line answers to many requests for help on line, they tend to avoid any odd desktop configuration variables.
4) There's still a few folks doing the FUD balderdash. Ever tried to actually get customer support from Microsoft? Ever bothered to look at all the sites that tell you the equivalent applications in the open source world? If you truly need 100 percent compatibility with microsoft applications such as office, you need to run windows and microsoft office. I never had any issues exchanging word documents with clients when using open-office and later Libre-Office. If we were using macro laden spreadsheets my results could have been worse. If you use the most obscure hidden features in photoshop, darkroom, or premier you need your Adobe subscription. For the vast majority of folks though, most all you need is out there unless (as I posted earlier) you require something that just isn't well supported in a way you like under linux.
4a) If you want to see if an app is good enough, most all of the open source applications are available for Windows as well as linux. You don't have to change operating systems to change your office or photo applications if you're tired of the subscription model for software.
5) You don't need to worry about viruses with linux. Sadly not true, the first virus (actually a worm) was on unix networks. Viruses are very rare. Clam-AV is a good virus scanner. It's not a big thing, but just as with windows, not opening up every port on the machine, staying behind a router that does NAT (if you're on broadband and have or can have multiple machines / TV's connected you're likely behind a NAT firewall), and running a local firewall are all things that are never bad decisions no matter what operating system you are using. Apply patches. Linux tells you when updates are available, you don't have to put up with being in the middle of a zoom conference and have your system arbitrarily do a 20 minute update and reboot without asking if it's OK.
6) But, but, but, if I don't have a microsoft approved browser I can't do all the online things I have to do!!!! Ever noticed that most of the world does the same stuff on their phones? Apple and Android don't have microsoft browsers, go figure. I use Brave as a default browser as it tends to scuttle the overlords constant attempts to monetize web use. Firefox work fine, so does Chromium. Chromium is NOT chrome! Chrome is a google data harvesting app hidden in a browser, chromium is open source.
And finally, use the tool that meets YOUR needs. Or have more than one tool, refurbished computers are often a really good deal, and being one or two CPU generations behind typically doesn't really matter in terms of actual performance. Replacing an old spinning disk hard drive with an SSD, and maybe bumping up the RAM will often give a huge increase in performance at a much lower cost than buying the latest and greatest machine regardless of your operating system.
Cheers,
Stan