In my experience, RR is much more critical. Readers there generally have higher standards, and are not afraid to voice their complaints.
However, I don't understand why some people call it toxic. I've been posting over there for almost two years and have been reading for much longer, and have never seen a comment that was simply "mean". There were plenty of critical reviews and negative comments, a good portion of which were wrong, but it was extremely rarely negative for the sake of being negative. It is almost always justified criticism from people who took the time to explain their issue with what you wrote, and are willing to discuss it.
I would disagree with the notion that RR is not for amateurs. RR is for those who want to improve their art, and are ready to take in the necessary criticism. Perhaps “not for the faint of hearts” would be more accurate, for it is when your writing is bad that you have the most to gain from the RR community.
If you post on SH, you will get 99% positive messages, giving you that happy feeling that your work is appreciated by everyone. Almost no one will rain in your parade, even if what you wrote is terrible. Those who will, however, are often less articulate and insightful from those you get on RR.
On RR, you will get 75% positive messages, with the 25% of negative one being long, detailed and harsh. They are never fun to read, but they can help you improve tremendously, and I find it also gives the praise I receive more weight.
In conclusion, I agree that RR is more critical, but I consider that one of the strong points of the website. I suppose it just depends on what you want from your readers, if it is friends that will support you no matter what or people who will judge you and try to help you improve, no matter whether you want to or not.
