There are different levels of distros. Like Android is a linux distro where 99% of users never touch a command line. You can also use Debian/ubuntu and debian/ubuntu based without ever using a command line too. Antigros and Majnaro are light with CLI. Arch will require some command line from time to time, and Gentoo-based can be used without command line, once you get the hardware rolling. Chrome OS is built on Gentoo and might offer some luxuries over Gentoo for an end user, but it's not as fast of an OS, overall, nor is the development as quick. Slackware without ever using command line... ehhh I doubt it. Redhat/Fedora, possible. Light use at worst.
The reason why terminal is still used, is because it's super quick and lightweight. In most cases, you'll have both options of the GUI and CLI method to do the same tasks.
Pros: Security, stability, memory and overall resource management, customizability to all extremes. Huge software library. Cross platform applications you are used to on windows or mac are.... well, cross-platform, so you will find them under linux as well. Because the free software mentality exists throughout different linux software projects, you can have everything update, and not just the system files automatically, or a few different ways under different app management tools. You have a choice of different desktop environments, some that look and behave just like windows, some that look and behave just like MacOS, some that are completely original. After all, the startmenu system from windows, the dock system in Mac, the menu bar in Mac, were all concepts used years before in unix/linux systems.
Also, a lot of aussies use linux because they can bitmeter their webtraffic better. The filesizes are smaller for the same programs. But these are intermediate tricks.
Cons: Unless games are built on a cross-platform engine, you have to either hope a GOOD wine profile exists(otherwise you may need to build one yourself) or dualboot into windows to play it. Some proprietary drivers require certain kernels, and if you don't test your OS with a liveCD installer (in the live mode) you might find yourself needing to try some less than stable configurations(although YMMV, as many run unstable branches of software, and have perfect stability, while others may not.) Also because linux is a GPLv2 license(basically, free to use, share, modify, distribute) some hardware vendors do not support making device drivers. It's rare, but you can run into issues there too.
All OS'es work similarly. So the learning curve is basically the filesystem(which is unix-like and similar to BSD/MacOS/iOS/Android). Depends on which distribution you use and what flavor/variant of a distribution. What Desktop Environment you use also can add to the learning curve. I run XFCE, some say it's the most windows-like as far as how it functions. KDE looks a lot like windows too, both share a lot. KDE is a resource hog similar to windows UI, where XFCE is lighter. Then you have a lot of stuff in between.
Try a LiveCD of Ubuntu MATE 15.04 if you get bored and have an extra gig of bandwidth. No need to install it, in fact, I wouldn't. But get familiar, see what you think and keep in mind that a full install runs much better and faster. Watch some youtube video reviews.
