It's obviously not necessary, and there are other free editors and IDEs. But in my experience, it is the best option.
I've used both Vim and Emacs and played with Sublime and Atom a bit. Those four editors allow you to highly customize your programming environment. Which some feel is a necessity.
They're all great, but you will miss out on some features that no one (that I know of; if you do, please share) has been able to properly recreate in a regular editor. Mainly, intelligent code navigation and completion. These are the most useful features that I've used, and PyCharm does them **almost** perfectly.
You'll spend much more time navigating code than you will typing code, so it's very helpful to be able to hit a keyboard shortcut and jump to a variable or method's definition/declaration. When you are typing, the intelligent autocomplete will be a big help as well. It's much more useable than the completion engines in editors because it only provides completions which are in scope. There're also Ctags and Gtags available for text editors but they are harder to use, must be customized for every language, and with any medium to large sized project work poorly. Though YMMV.
When it comes down to it, I prefer having features that work really well than the ability to customize. Download the community edition and see for yourself if it works for you. Especially for a beginner, it will save you the time of learning tools, which isn't as important as learning the language, because the UI is self-explanatory.
P.S.
I would find it unusable without the IdeaVim plugin. The keybindings of Vim are just too good to give up.
I should also mention that Jetbrains IDEs are very customizable themselves. The IdeaVim plugin even has a dotfile.
You'll also find videos on YouTube where programmers try to discourage others from using them because of the distracting number of panes. Though it has a distraction free mode and even without that, if you use it sensibly, you can have it only display the editor and tabs.
