This was hard. The books sets up a great mystery in the beginning and then completely ignores any notion of a plot for three quarters of itself. When you get to 75% and still have no clue what the book is actually about, there must be something wrong.
Don't get me wrong though, KSR's Mars Trilogy was in many ways similar, with long descriptions of the martian landscapes and characters' inner monologues, but at least there was some plot moving forward. In this book you get loads of ideas of how colonizing and terraforming of the solar system could work in 5 pages and then main character running with wolves for 15 pages. I'm not making this up!
Have I mentioned annoying main character? 140 year old woman, who designed entire worlds, lives on Mercury and has quantum computer implanted in her brain sounds interesting. But not when she behaves like 20 year old brat and yells at people to make her arguments.
So, if you want an amazing book written by Kim Stanley Robinson, go with the Mars Trilogy.
Redshirts are, as other John Scalzi novels, a quick, fast paced read. I laughed few times, but it's more serious novel than I expected it to be.
I'd rate the story itself as 3/5, since it's too generic and little Red Dwarf: Back To Earthy to me. What adds the forth star are the last two codas, that add the emotional aspect the novel itself lacks a bit.