A question to the creators if they are listening. What is this medium.com you say have inspired you? I followed the link but it asks permission to access to the list of my followers on twitter even before I can have the slightest idea of what it is. I checked the read more thing, but after an empty tagline it starts telling the story of guys I don't know, and I have no time reading their stories.
The main concept in medium thats inspired me here, is their wysiwyg style editor (https://medium.com/about/df8eac9f4a5e) over markdown... although mine is a tad more minimal, I'd be lying if I didn't say they had a big influence on ZenPen.
I am working on an open-source app inspired by medium. Hopefully this should be done in a week's time. Here is work in progress: http://i.imgur.com/ZYWRc8k.png
I'll also borrow your/medium's idea of showing the toolbar when text is selected.