I love the site, but I have yet to have any of my submissions get reviewed by anyone else. Great concept, but maybe there is more they could do to encourage experienced developers to review the submissions.
I signed up last week and have been using it to learn Erlang. I have some experience with Elixir so Erlang isn't totally foreign to me. I'm experienced dev and have only commented on 1 submission. The problem with commenting on submissions is that I'm learning the language as well so there lacks the authority of knowing what would be the <INSERT LANGUAGE> way.
I had a lot of good feedback on some Ruby problems I worked on a few years ago. I'm guessing it's highly dependent on having a community for each specific language.
Same, on Ruby and Lua I've gotten good feedback, but not other languages. I think it helps to comment on your own stuff and ask questions if you're unsure about your solution and if there's a better way.
I've written ~15 of the higher-level reference exercises for Elixir on Exercism, and do try to comment when I can, but my day job keeps me from it a lot of the time. Some sort of reminder system would definitely be great, especially as more people use the site.