This is a personal perspective, that of an end-user. I was not involved in the the development of Linux, nor have I ever spoken to anyone who was. I have, however, been using and programming computers since the era of main-frames.
In the era of mainframes, the computer languages most popular were those highly-suitable for computation. FORTRAN was favored by the scientific community, and COBOL, I believe, was popular with the business community. I don't remember what the operating systems were. In the era when end-users never got past the window where you turned in your program, punched in paper cards, the OS hardly seemed relevant.
When non-mainframe computers first became available, the first machines available seemed like mainframes for individuals. This was an era dominated by Digital Equipment Corporation, and I remember the introduction of machines like DEC's PDP-4, which had an unheard of amount of memory, all of 4000 bytes, most of which was available to the programmer. The PDP-4 was quickly followed by the introduction of the PDP-8 and PDP-16, with an exponential growth in the amount of memory available to programmers. This brief era also saw the introduction of user-friendly languages such as BASIC, which individual computer enthusiasts could easily master.
Eventually the idea developed that one powerful computer (referred to as a server) could handle many clients (end-users). The operating system favored by most of these servers, usually was one of two flavors of UNIX, one developed at Berkley, and one by ATT.
From the perspective of the end-user, these Unices had both advantages and flaws. Most importantly, they seemed quite robust, crashing relatively infrequently, and easily rebooting. On the other hand, they were patent-encumbered, not totally compatible, expensive, and huge. It is during this era that Linus Torvalds created Linux, a small, non-patent encumbered, Unix-like OS. It was free and small and simple, making it ideal for devices other than huge computers.
Subsequent to the creation of Linux, computers became simultaneously smaller, more powerful, and less expensive, and the idea of a "personal computer" truly took hold. Needless to say, for a true PC, the client-server model was less relevant. In those areas where reliability was the primary concern, namely banking and finance, institutions stayed with Unix or slowly switched to Linux. But due to the entrepreneurship and marketing skills of Bill Gates, the dominant operating system for personal computers became Microsoft Windows.
While Microsoft was able to make their Windows OS suitable for non-sophisticated users, it was never a very inspiring OS. As a result, increasing numbers of computer enthusiasts, like myself, have attempted to use Linux as an OS for both desktop and laptap personal computers.
Ubuntu has been billed as the Linux distrubution most likely to replace Windows on the desktop and it seemed natural to try Ubuntu-10.04 first when I decided to leave the Windows world. That first experience was not entirely encouraging. I do not want to criticize Ubuntu, I think they offer a fine product. However, Bill Gates, long-time CEO of Microsoft, may never have had an original idea in his life, and he certainly didn't seem to know what the advanced power user wanted. But he was a pioneer of the idea that once the operating system was installed, the end-user should simply have to turn on the power switch to start enjoying it. Never, when running Windows, in contrast to Ubuntu-10.04, did I have to worry if the wireless would work, or if I could play a DVD. In fairness to Linux distibutions, the reason many have problems like these, may be that many of the obvious solutions are patent-encumbered.
One of the reasons for supporting Linux over Windows is that Linux is largely based on free, non-patent encumbered software. I believe that, in time, non-patented solutions for virtually everything you want to do will be found. The more Linux users there are, the more quickly that time will arrive. And when that time arrives, there will be still more Linux users.
There are a huge number of Linux distributions to choose from. In addition to Ubuntu-10.04, I also have used Fedora 14 on a 32-bit personal computer (a Dell Inspiron 1525) and Fedora 15 and 17 on a 64-bit personal computer (an HP Compaq CQ62). I bought each computer for approximately $800 in the USA. I currently use Ubuntu-12.10 on a Dell Inspiron-15R.
In my opinion, in 2012 Linux offers, for many end-users, a very competitive and even possibly better OS for the desktop or laptop than Microsoft Windows. It needs be noted, however, that the world is not standing still. It is clear that currently, the modern world is focusing less on desktops and laptops, and more on tablets, phones, and other mobile devices. The top Linux distibutions, Fedora and Ubuntu, both are trying to position themselves for positions of strength in the future.
Fedora 14, released at the end of 2010, used Gnome 2 as it's default desktop interface. Starting with Fedora 15, the default desktop interface was changed to GNOME 3, which was not totally compatible with Gnome 2, but was perceived as necessary for future development. In particular, it was thought that Gnome 3 and a new idea that accompanied it, gnome-shell, were more suitable for devices with touch screens, and thus necessary for the future.
About the same time that Gnome 3 and gnome-shell came out, Ubuntu also switched from Gnome 2 to a new desktop interface, Unity. Unity, also was thought to be better-suited for phones, TVs, and similar devices.
Although my first experience with Ubuntu-10.04 as a Windows replacement was frustrating, as outlined above, I either got used to Ubuntu, or subsequent releases got better. I find Ubuntu-12.04 a very reliable OS, but actually prefer Fedora's default Gnome3-shell to Ubuntu's default Unity interface. The solution was painless and obvious. Following the directions of Fili Wiese, it was possible to quickly install Gnome3 shell under Ubuntu-12.04. This has worked for me without problem for nearly four months as of the time this was written. Another distribution which is based upon Ubuntu-12.04, but has a Gnome3-shell interface is Deepin-12.06. I have not thoroughly tested it, but it looks very professionally done.
All Linux distributions I know of load software to your computer from other computers which are repositories of the various programs. When the software loading program you are using (apt-get for Ubuntu and yum for Fedora) reports that a particular software package is unavailable, it means that the package is not available in the repositories it has checked. Both Fedora and Ubuntu initially check only a limited number of repositories for available programs. The only repositories they check initially have a very strict view on what is non-patent-restricted software. This is why initial installations of Ubuntu and Fedora will not play DVDs. A solution to the DVD problem is described in the "problems and solutions" link below.
One of the pleasantest surprises after I switched from Windows to Linux was experiencing how fast Firefox ran under the latter compared to the former.
If you think my experiences tackling Linux problems may be helpful to you, please continue reading about specific Linux problems and solutions.