If the title carries meaning for you, you are, arguably, the intended audience.
I found the main story to be a fun little meta-fictive romp, and not a lot else. In tone it very much reminded me of his earlier novel, Agent to the Stars–deeply aware of, if only to have fun with, genre conventions. As utterly unconcerned with the “science” part of “science fiction” as its purported source material.
There are certainly far worse ways to spend a few hours, though there are many better ones as well.
I was intrigued, though, by the three “codas”. Obviously, John felt it necessary to write a little apologia for it. And I was doubly intrigued when a review I read of the book a couple of days before I got to it myself suggested that the codas were a waste of time.
In fact, I think the codas–specifically, the second coda–are the best part.
Now my gut reaction to writing in the second person is something in the general neighborhood of derision. Tell me you’re doing it, and I will suggest you are making a mistake. Tell me you’ve already done it, and I will make a note to avoid your book. Admittedly, if you get me to read your book anyway, and I might actually like it (thank you, Mr. Palahniuk), but my default assumption is that it is going to be annoying and precious.
But I can’t imagine the second coda to Redshirts working as well from any other point of view. To ask the reader–especially one who has some idea what might be coming–to empathise with the weirdness of the situation the character finds himself in pretty much demands something as jarring and weird and annoying as second person narration. So I think it not only worked, but was the only way it could work. So I actually found myself more satisfied after the codas than before.
I’ll note, just because I’ve started paying a little more attention to this in my fictional choices, that I believe the book fails the Bechdel Test. I think there are only two female characters in the whole thing, and they never talk that I remember. Just so you know.