Which is the most functional interface is a matter of opinion. Ultimately you would have to try different ones until you found one that you liked. This is itself an advantage of Linux - that a variety of window managers and desktop environments are available to suit different tastes. A person who wants lots of customisability may prefer KDE.
http://www.kde.org/workspaces/plasmadesktop/
Someone who wants something more minimalistic and faster/more lightweight may prefer xfce.
http://xfce.org/about/screenshots
For ease of use for the beginner, Gnome has often been favoured, although the new Gnome (Gnome 3) is controversial. Some folks love it, others hate it.
http://www.gnome.org/gnome-3/
One advantage of Linux over Windows in my opinion is package management.
Whereas on Windows you have to go to the website to download a particular app, on Linux you download all apps from a central repository. This means you can update your entire system with one command.
It also means that you can be more confident that you are not installing malware, because your distribution will not allow a piece of software to enter the repositories if it is not trustworthy. Also, one of the advantages of opensource software is that it means that your distribution will compile it's own binaries from the source code and it can check the source code for any malicious code or security vulnerabilities.
The iTunes app store is actually modelled upon this idea of getting all software through a central repository.
There are alternatives to iTunes - rhythmbox, amarok, banshee, audacious, vlc, clementine, guayadeque and more.
Some of these have features that iTunes does not - or at least did not last time I used it.
For instance, iTunes only supports a handful of formats. Good formats like Ogg Vorbis, Musepack, Flac, Webm are not supported, at least not natively.
Some of these can automatically fetch info from the internet on each song on the fly such as the lyrics, a biography of the artist from Wikipedia, photos of the artist etc.
Guayadeque can record internet radio streams.
Linux allows me to use my file manager to drag and drop files onto my portable music device. I don't have to do everything through iTunes. I remember once when I used to use iTunes and there was a bug and I could not put new stuff onto my ipod for a couple of weeks until apple got round to issuing a bug fix update. Also, syncing was taking ages - if had been able to drag and drop the new song onto the ipod it would have been much faster but no I had to do a full sync everytime.
The hiding of files is useful, since otherwise your home folder looks cluttered.
ls lists all non hidden files
ls -a lists all files including hidden ones.
Or you can set your preference in your file manager or alternate using a keyboard shortcut.
Open source is a fundamental aspect of Linux, so many of the top Linux apps such as Gimp (photo editor) have been ported to Windows.
Since Windows is not a Unix style operating system, the fundamental tools are different.
cron, rsync, shell scripts, grep, ssh - all of these things are great.
shell scripts allow you to automate tasks.
cron will run scripts or perform certain tasks at certain times.
ssh allows you to connect computers over the internet in an incredibly secure manner and all encrypted so no one can read the data - keeping your personal info private.
I know there is an ssh client for windows (putty) but i don't think Windows can act as an ssh server? Not sure about that.
nfs is the fastest network filesystem there is but nfs does not seem to work very well on Windows so most people in a mixed environment will use samba.
Samba mimics a Windows file server so well that it is used in big enterprises. Unlike Windows server, it is free but it can get the same job done.
http://www.samba.org/
My advice is to give Linux a try and make your own mind up. It is free so you have nothing to lose.