I joined this site as a novice unpublished writer two years ago. There were/are numerous groups I could join, that best suit my writing interests. The critiques I have received have been extremely insightful. Unfortunately I'm one of those authros who think I'm so very clever when I write something - the critiques have shown me that I'm not so clever and ways in which I could improve my writing.
I've now done quite well having been a finalist in six national short story contests (yet to win though) and most of those where greatly improved through the critiques of those on scribophile.
That said, the critiques one gets can vary considerably, depending not only on the writing experience of the critiquer, but their capacity to have insight into how one can improve the writing and where/why the writing was weak
The site is free nut you can pay a modest premium to get added benefits, which I elected to do. You can message other authors with whom you have developed a collegial relationship and arrange more consistent critiques of your work.
I find this site to be far more helpful than the writers group I attend at a writers centre.