I first purchased Byword years ago and was pleased with its clean and elegant UI. I’ve bounced between Markdown writing apps quite a bit since then, but recently downloaded it again on all my devices (iOS and OS X) just to play around. Not too much seems to have changed at first glance, but significant iOS 9 changes have made it a great option again, with additions like Spotlight integration and multitasking/split screen support.
It won’t do all the things an app like Editorial can do, but it’s great at what it does. It’s decidedly simple, but that’s not a bad thing at all. I’ve been using it for certain types of personal writing (still using Drafts with custom actions for blogging) and I’ve been delighted with the updates.