The thing I like about Atom is that customization and package development (LESS and CoffeeScript) should be familiar for any web developer.
Having the inspector available is really useful for debugging purposes, and also for figuring out CSS selectors for UI customization.
One thing I hear people complain about is that package development is in CoffeeScript. While this is not strictly true (you can write things in JS), I can see why CS was chosen. There are some nice DSLs that can be exposed via CS but not JS.