I've Said it before in other threads akin to this. Linux is fine. I've used it. However I feel that as far as user friendliness Linux has a LONG way to go. Sure, Linux is malleable, But you need to be very comfortable with computers to really understand and harness the power of linux.
However, Windows is very user friendly. It's a bit more friendly and while there are distros of linux that use a Windows like interface there isnt as much easily accessed functionality. Most common end users would be terrified of the command prompt style interface.
And after all who can blame them? Many people that use computers are not well learned on how they work and there's a fear factor that, If they do something wrong the thing goes boom. XD
Of course most of us younger people know that's not true but the old folks would freak out if you left them alone with a linux machine more than 3 minutes. I myself prefer Windows. Why?
Because Windows is the more common system. It's well supported so I dont have to write a program for myself to make the computer do what I want it to do.
In essence I see nothing wrong with Linux. It's a stable environment which isnt exploited as often as windows is. It's bare bones kernel and systems ensure that your machine is being used more for your programs and not the System itself.
For example, In Windows, the system may hog up to and not limited to 60% of your systems resources.
In Linux, however, the system may only use about 20-50%
But of course, The resources needed for the system is dependent upon how you are using the machine. So dont take these percentages as if they are even remotely accurate. I'm just making a point here, not trying to put those numbers in the air as if they were correct.