Recs.
Updated
SpecsUpdate
Pros
Pro Extendable
Due to its modular design almost any aspect of the editor can be changed. Even seemingly core packages like the one's taking care of search and replace functionality can be forked on GitHub, changed and replaced in the editor.
The Documentation for creating new plugins is also great and thus it's easier for developers ti jump in and create plugins for Atom.
Pro Beginner friendly
One of the goals of Atom is to be a text editor for both experienced and beginner programmers. You can add keyboard shortcuts, change themes, install plugins, and change core settings by clicking through a GUI, or by manually editing config files the old-fashioned way. It has the added advantage of being built using the same engine that powers Google Chrome, so actions like opening and closing tabs feel familiar, even to new or non-programmers.
Pro Command line integration out of the box
Installing Atom adds two command line commands - atom and apm. The first one runs the application itself and the second one is the Atom Package Manager that's used to add and remove various components from the package listing. While these features can be set up with other editors as well, Atom takes care of them out of the box.
Cons
Con Has difficulty with large text files
Tends to crash or hang with large >(10MB) text files, making it less useful as a general text editor.