Open source, Free, "Hackable"
Battery hogger, slow
Atom feels as heavy as an IDE. It has a lot of plug-ins but I find that many feel broken. Looking at Activity Monitor on Mac, you can see it uses a lot of battery, and this is a dealbreaker for me. Unfortunately it's the only "IDE" for Julia (which, ironically, is a high-performance language) so I stick with it for these tasks.
Awesome effort/work by the community though. It's too bad I don't agree with the choices the community had to make because I personally think this could have become a true "Emacs for the 21st century" text editor.