Interesting! I went and made a little chapter to get a feel for the site (haven't gotten to the titular pickle yet, my writing style tends to result in wildly unpredictable deviations from my initial concept,) and had a couple thoughts on bugs and potential improvements.
-Apparently chapters have a limit on how many characters they take, as my first chapter lost like 2/3 of what was there. *copies chapter to txt file pending resolution* I mentioned it under the bugtracker chapter.
-There's a spot on the main page for popular and trending stories, but it'd be cool if there was a spot for Most Recent stories on the homepage.
-Personally, I'd like it if you could post a short description of your story at the root story level, where it shows all the subsequent chapters. That way you don't need to use a chapter just to provide a summary of your work, or to provide more detailed instructions for potential collaborators (example: "Hey guys this story is gonna be the same half hour told over and over, told from different perspectives each chapter")
-I found myself wanting to resize the text input box while writing my chapter, and the ability to preview would be nice. Preview lets me see how it'll look when others see it (i.e without Firefox's red squiggles under words I made up) and it gives me a working copy to refer back to while I make edits, so I can read a bit and edit it, then read the next bit and edit that, etc.
-If feasible, it'd be cool if there was an email notification whenever somebody adds to and/or comments on your story (or stories you are interested in.) Or at least a section on the site itself that tracks such activity.
All in all, looks fun!