Not that hard, specially if you have used some old windows releases (using the console is pretty much like old DOS
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). I would say that ubuntu is a bit more user friendly, since almost everything is handled through the graphical interfase. In fedora the console is used more often, but is not very frequent (unless you want to). I think that linux is not harder than windows for common tasks. It is a bit like PixInsit. You have to get accustomed to it.
On the drawbacks, when things go wrong, they really do go wrong. Fixing stuff ussually requires more time and effort than in windows. Having said that, the forums are a great source of help. Almost every time I had a problem, googling it gave me an answer. Sometimes, you'll get a solution that works only in one distro, but knowing the basics you can adapt it for your use (for example, the command to install things from the console in ubuntu/debian is apt-get, while it is yum in fedora/red hat).
I encourage you to try them in the live cd mode. Run both ubuntu and fedora, in their gnome (or unity) and kde variations. Then, install what suits you best.