For some reason, people consistently feel that one operating system is more difficult to use than some other operating system. To me, this is a load of dingos' kidneys. I fail to see how Linux is more difficult to use than is Windows, or how DOS is more difficult to use than is Windows, or how Windows is more difficult to use than is a Macintosh. In all of these systems the setup is rather easy, software management is rather easy, just about everything is rather easy. The perceived difficulty is in the differences that exist.
So, if we look at Ubuntu the installation is rather easy. Let the system use all defaults and just keep hitting next. Before you know it, things are set up and ready to rock. Unless you have some strange hardware, everything is fine. The same can be said about Windows, Macintosh, or even Haiku. Software management is a breeze as well. On Linux, you go to add/remove software or whatever it is in the latest version and you simply click click done. In a Windows environment, you go to a store, find what you need, buy it, take it home, install it with a few clicks and you're done. Pretty easy, right? Macintosh systems have some options. Basically, you go to a store and buy what you need similarly to Windows. Most often, you can drag and drop the application icon into the "Applications" folder and things are ready to go. Some applications have installers and the default options can be followed. There are plenty of applications available for all three platforms on the web, and on Windows you have cigwin which can yield a lot of free software, and you have MacPorts on Macintosh. These are all similar. There really isn't much difference or difficulty. Things change when you tell people very particular things.
Example one: Windows has malware, and that makes it more expensive and harder to use. Well, the counter point to this is simple: good safety practices should be used on any system regardless of whether or not you have a security suite installed. You should also not run your system as root/administrator all the time, regardless of which OS you are using.
Example two: Linux is harder because you have to use command line or you have to have programming skills. This is complete FUD. I haven't had to use any command line or programming skills outside of them being a hobby of mine. I didn't need it to set anything up or to install anything. A graphical way is almost always available.
Example three: Macintosh's UI is crap/awful/whatever (and they do have two button mice so don't be a troll). You are always free to change it (Macports + rooted X11 + KDE). The same stands for Windows (simply change the registry entry for shell) or Linux (install whatever it is, and make a .xinitrc and type startx). Not everyone is satiated by the same things and this is the very reason that things improve.
Example four: OSX/Windows/Linux has awful driver support. Drivers have little to do with the OS. It is not the fault of Linux kernel developers that drivers are missing for certain pieces of hardware. Blame the hardware manufacturer for not supplying it. The same can be said for Windows and OSX. As time goes on, more and more hardware manufacturers are starting to supply drivers for Linux and OSX, and more are starting to provide installation driver discs (also known as F6 drivers) for Windows. This helps everyone.
Example five: "If something goes wrong in Linux/BSD/Solaris it is really hard to fix!" PLAIN BS. If it were any easier in OSX or Windows, I would be out of a job in computer repair. You have to find a text file? Oh noes! In Windows, I have to find a registry entry. In OSX, I either have to find a text file or some config applet. Big deal. Every OS has a friggin search function for that stuff, whether it's find, spotlight, or pressing f3 in regedit.
Here are the real facts. I am in computer repair. I deal with all three major OSs every day. I am also a college graduate and had to learn all three major OSs. I am well versed in all three. I can sell all three to anyone who walks through the door. The key is not which is "easier," the key is taking the time to show people how to do whatever it is those people need to do. Every OS is different, and they are all equally easy. People are more accustomed to Windows, and they often have some trepidation about switching to something else. Likewise, an OSX user will have some trepidation due to FUD about Windows or Linux. When the time comes that another system may suit a user's needs better than what that user is current using, they are willing to switch if someone else is willing to show them how to accomplish the tasks they have at hand. What should be taken into account is that each OS has certain things it does well.
Windows: Great for the business environment, great for gamers, great for CAD. Windows and MS Office offer great business collaboration and interoperability with Exchange servers. Windows also has the best 3D performance out of the three top OSs. That 3D performance makes Windows ideal for CAD and gaming.
Macintosh: Well suited to 2D artwork, or lighter 3D artwork. This is in part due to the applications available for OSX, and also due to the wide array of tablets and other devices available for the Macintosh. In general, Macintosh systems are reliable and seem to have become fashionable. Otherwise, they are rather generic and perform that way in a variety of situations making them fully capable of suiting most common computing needs. They're UNIX underbelly and ability to come with stats close to a Cray (on newer models a Macintosh can come with 12 processor cores, all hyperthreaded, and all running at 2.93gHz, 64GB of RAM, up to four PCIe graphics cards, and several SSD all on RAID) make the Macintosh rather well suited to research and engineering fields.
Linux: First, Linux is scalable to a point that is kind of stupid. Linux can run mainframes and super computers, as well cell phones, and even less powerful embedded devices. Clearly, that gives it a wide range of application that neither Macintosh nor Windows can really deal with. Secondly, Linux has proven itself far more stable than its commercial competitors. Still, Linux lacks good CAD software, and good arguments have been made against Linux for tax, accounting, and other business related software not being up to par with commercial applications available for Windows and MacOS X. The general security, scalability, stability, and responsiveness of Linux make it perhaps the most capable general purpose operating system. So long as you are not using it for CAD, gaming, or certain very specific business tasks.
Verdict: Each OS has its purpose. Each OS is easy to use.