Atom just feels weird and broken. Make a new document - why is Edit -> Undo enabled when there's nothing to Undo? Press Command-Z - why doesn't the menubar flash to indicate that I typed a key equivalent? Control-click on an item in the tree view on the right - why does it only highlight after the menu is dismissed? Make the window bigger - why is there a flicker, as the content repaints after the window resizes?

Atom exists in an uncanny valley, and re-introduces tons of problems that the design of OS X has worked hard to avoid. I hope Atom doesn't succeed for that reason: it's a big regression in UI.