The site looks interesting and seems to have or have had a lot of activity. I've signed up (after reading quite a detailed agreement page... yowsa,) and will give it a bash!
The site might have "activity" but is it activity which is going to help you, or is it the activity of a crowd of unknown writers trying to get each other to read their works?
I hope you read the link that Medievalist provided in posts #6 and #8 in this thread before you signed up.