Despite the problems with Linux as have been pointed out so far, I have found Linux to be better than Windows and OSX, and not just because I hate proprietary software.
With WINE working properly, I am even able to play my ‘Windows-only’ games easily. Although that did take a while as I had to install a lot of 32-bit packages on my 64-bit system for everything to work properly.
I think the degree to which Linux is useful to you is dependant on how comfortable you are with using the terminal. If you put a little bit of time into learning how to use it, then you are able to troubleshoot your own problems much faster than you could on Windows (and presumably OSX, which I don’t have, but have had bad experiences trying to fix simple problems for it).
I am using Arch Linux, which may mean that some of these thoughts do not apply to all ways of using Linux, but the thing is that no matter what distro of Linux you use, there is the helpful community out there for when all else fails.
The one problem I have with Linux, and the open-source concept in general is exactly what @princec and some others have said above. There is potential in Linux, but people get too excited with the new freedom it brings and spiral off in many directions without getting anything useful done.
Perhaps one day open-source will become mature, and then Linux will be able to become the ultimate OS.