It's generally easy to figure out how the program works - you start with some paper, and every time you press Enter a new, linked page is created. From there, you can add options as you wish. Each option allows you to go to a new page to choose how that option branches out. Writing is easy and convenient, and you can always go back to the beginning.
However, there are a few other interfaces you can look through. You've got the Map, first of all, which is super nice. It allows you to see an overview of what you've got together so far:
Then you've got your Contents section, which is a bit more technical and allows you to see all the different parts of your document, as well as search it.
I think Inkle is a great tool, but it IS a bit buggy currently and it might be a bit harder for the implementer as, unless they're given access to the writing part of your document, they can't see the Map. This means that they can't see the overview, and have to click through as if it were an interactive story.
Twine starts out with a bit of a tutorial as soon as you begin. It tells you some basic info, and then you can go straight to the story-writing area, which looks simple and beautiful.
Secondly, there are no text editing options readily available. They must be done through tags in the text, which is alright but not quite as easy. No shortcuts.
However, you can share it in the more "techy" format, which is easier for those trying to implement your story. You can use the Publish to File button: