I like how you can use command keys to quickly toggle on and off the project file and current-file's-components browsers, leaving the "distraction free" * editor window for much of your work.
* yeah, there's a mode with this name that auto-wacks ALL the supplemental panels, AND the window frame. I don't usually go that far, but it does show that they "get it" as far as what many of us IDE resisters disliked.