My experience is limited. I first found Litopia several years ago but I couldn't find the forums for critiquing, not realising that these are hidden until a member has been on this site for seven days and has gain twenty (?) points.
I returned after Colin recently mentioned Litopia on another forum and his comment reminded me about Litopia. It was then I realised that the critique forums are hidden, which explained why I couldn't see them before. My feedback would be that it's nice to see the standard of people's work and the critiques given, even if I cannot post. With this in mind, I would have preferred the critiquing section to be open to view but with the post option blocked.
I have joined from another writing site which, I feel, is easier to navigate but has few members due to only taking payment and not updating the site for many years. So, any feedback I give regarding Litopia would be based on my comfort with the layout of this other smaller site.