I can only speak for myself. I started using Linux Mint for one reason only, I wanted to learn what the whole Linux thing is all about. Aber several months of using it these are my thoughts:
It's a great OS if you like to have more control over your OS than Windows grants you. And no, for an average user it won't ever be total control since during the last months of using it I more than once realized that I had no clue what the command I had just copied from some forum or blog or whatever to fix a certain problem would do exactly
So if you don't know the internals of the OS, which very few actually do, then it means more control than in Windows, but total control? No, not without very sophisticated knowledge of Linux and maybe not without being able to code.
What's also great about Linx, and that's also the reason I will probably keep using it besides my Windows 8, is the fact that it is always a good thing to have an alternative at hand. This way you are not completely dependant on Microsoft and it's OS.
When it comes to security Linux is a mixed bag for me. On one hand it's clearly more secure than Windows just because of the fact that all Windows versions together still have a wordwide market share of a ridiculous 90 %. So it's kind of logical that if you wan't to write a malicous piece of code you are better off writing it for Windows than for the 2 % or so that use Linux. And those 2 % even use various distros that probably cannot all be attacked by the same virus. So it is kind of nice to surf the web without having to fear that the next link one clicks on could probably infect the system with some kind of virus, trojan, whatever. But on the other hand that's also the weakness of Linux. Because everybody feels so secure when it comes to Linux nobody takes precautions to avoid a possible infection. There is no proper anti virus software out there for Linux and some especially bold people even suggest that it's not necessary to use a firewall on a Linux pc. Imagine just for one second that there would be an organization or just a group of people out there that would dedicate as much ressources to develop a spy software for Linux as they do to develop such software for Windows. Almost any Linux user would almost certainly fall victim to such a software because Linux users feel so superior that nobody seems to even imagine the possibility of viruses for Linux. In my eyes that's just outright negligence. Even Apple users are starting to realize that it might be a good idea to use a anti virus software even though there are not many viruses for OSX (which by the way is based on UNIX as Linux is).
Last but not least there is one more important advantage of Linux over Windows: It's completely free and almost any software for Linux ist free too. So you cannot really lose anything by trying it
But there are two big disadvantages of Linux that make it impossible for me to replace Windows by Linux, those are software diversity and hardware support. In case of software diversity it's crystal clear that no OS on this planet comes even close to the staggering amount of paid and free software for Windows. To tell it in the words of Apple: There is not an app for everything, there are at least 20 pieces of software for almost any type of software one could possibly imagine. No comparison to the agony you go through if you are looking for the one special piece of software on Linux and in the end, after having finally found and compiled the only piece of software that's available for Linux, you find out that this program does not even come close to the functionality of the available Windows programs. And when it comes to hardware support the situation is not so different neither. Ok, most hardware does run on Linux. But it does not offer the same functionality like the very same hardware does under Windows. E. g. no support for the driver features of my creative sound card, not all printer settings available, no support for hardware buttons on devices, no support for the usb port of my router, the list could go on forever.
So my conclusion is as follows: Linux is a great OS and it is absolutely a good thing to learn it and have it at hand as a (free) alternative. It is also great for running old hardware, especially after Microsoft has practically killed Windows XP by not patching it anymore. But if I had to rely on one OS only it would definitely be Windows because only on Windows I can do everything I want to do. If you configure Windows correctly and run it on appropriate, decent hardware (no cheap supermarket pcs) it just works. You boot it, you are productive and you shut it down afterwards. No need to figure this and that out before you can start working.
That's my point of view. Of course everybody is free to see the whole Windows vs Linux thing differently