This might interest the writers among us. The Mote in God's Eye is a very famous SF novel written by Larry Niven and Jerry Pournelle back in 1973. They sent the manuscript to Robert Heinlein to check over. Heinlein's regarded by many as the greatest SF author ever, and at that time he was at the height of his powers.
Heinlein was so fascinated by The Mote in God's Eye that he spent five days reading and critiquing the ms, then he sent back a 17 page letter that clinically pointed out Niven and Pournelle's copious errors.
Quite by accident I discovered Heinlein's critique is online at The Virginia Edition. Virginia was the name of Heinlein's wife and this appears to be a site publishing Heinlein's complete works. In any case the link goes to a PDF sampler that includes the critique. Open the PDF, scroll down to page 15 and start reading.
What struck me is that Heinlein's critique reads much like the best sort of responses that you find within critic groups these days. The difference being that this one's written by one of last century's most successful authors.
There are phrases in there that will resonate with most authors, and will definitely resonate with my literary agent. Phrases such as, "Your story begins on page 100." Heinlein lays into Niven and Pournelle for their poor English (two ultra-respected authors, mind you!). He was a former naval officer and he dissects their naval etiquette in detail. But mostly it's the way he thinks in terms of what makes a book work that I find instructive. Plus these words of sage advice: "Cut, cut, cut."
I'd suggest reading the book first. It's long but will reward you. Then read the critique. You can actually see where Heinlein's advice changed the novel.
The book went on to become a bestseller.