I really like the concept of Atom, but it always feels slow compared to VI. I think it's psychological though, because I can't point to any part of it and say "This is slow".
The other reason is slowness to open a single file from the CLI, it seems Atom doesnt reuse the already open shell like sublime does, there was a tracked issue for that one.
I like that it's more foolproof, though. Granted it's a product built for developers, it's nice to have a GUI for installing themes and plugins, and for configuring it. This aspect is what keeps me from switching to Sublime.
1. Opening large text files 2. Some frequent changes in one of the files in the tree being made by a different process