I stumbled across WriteOn a long time ago when it was still new, and it evolved over time with a lot of ups and downs along the way.
How it works
You post a story to WriteOn and either choose to share it or keep it only for yourself. There is a cover builder that Amazon allows you to use if you aren't interested in having a cover built or if you simply haven't had time.
It is a workshopping website where people are able to give you constant feedback about how your story is coming together. It isn't very useful for proofreading or direct content feedback, but it can be excellent for ongoing feedback about what is working and what isn't.
It is designed around a sort of quid pro quo model, but this rarely works effectively on the actual website itself. The problem is: most people are there to write their stories and don't care about giving feedback for anyone else.
This feedback style leads to problems within the community where people can feel neglected when they work hard to help others and see no comparable feedback for their own work. It is a purely open-ended feedback system with no requirements or investment. In general, I've found that some authors have thrived in this system, and many others have suffered.
It is also an online forum for people to express their opinions, which means that hostility and trolling is rampant. Many people have turned away from WriteOn simply because the most hostile users aren't being removed fast enough and the negativity is broken.
The thing about communities like this is that it is a great place to build your own smaller communities. I've made several life-long friends from this system and formed my own mastermind groups out of it.
It is also great for workshopping and posting a living and breathing document that people can interact with. When you do have your own small community, this is a great place to bring people to your writing and allow them to give you feedback.
Overall Grade: A-
Don't take my word for it! See for yourself!