Maybe the only thing I dislike in Ghost is that the browser spell checker doesn't work with it. I know that many people dislike spell checking, but I like it a lot, specially when writing in a language other than my Spanish mother tongue.
The problem comes from the component used to do the Markdown edit widget, CodeMirror, that it's not recognized by the browser as an editable component. Ghost developers have already said that they are replacing it by a spell checker compatible version soon, so it wasn't a blocking problem for me, but still a minor irritation.
And then I found this sell checker hack for Ghost, a Chrome/Chromium extension that enables us to choose between the native CodeMirror widget, incompatible avec browser spell checker, and the raw text area field behind it that allows using it.
I guess that next Ghost version (Ghost 0.5) will eliminate the need for this extension, but until then I have this hack installed in my Chromium browser and I love it!