I wasn't impressed. Atom is a web application (HTML, CSS, JS) masquerading as a desktop application and true to apps of that nature, it's heavy, slow, and resource hungry compared to its proper native counterparts.File sizes do a great job at highlighting this difference. Two of the most popular Mac programming text editors, TextMate 2 and Sublime Text 3, weigh in at 32MB and 28MB respectively while Atom is an unnecessarily hefty 219MB — a full 7x more bulk. To find a native editor that heavy, one has to download a full-blown IDE with everything but the kitchen sink like Coda. RAM consumption stats tell the same story: Atom gobbles up an unreasonable 225MB of RAM after a cold launch while TextMate and Sublime only take up 20MB-35MB of RAM doing the same.Of course, the other big side effect of being a web app is that it doesn't *feel* native. UI elements are all custom-styled, often behave differently than they do in the rest of the system, and just aren't as responsive.All in all, Atom is a disappointment, particularly coming from the same company that made the fully native and very nice Github for Mac git client. It would've been amazing had it been written with proper desktop technologies like C++ and Qt5, but its Chromium-based core kills it.