I think most of the 40k novels are alright, but it all depends on what you are expecting when you pick them up. Some of them offer a much deeper experience than others that's for sure .
Ive enjoyed everything ive read so far(cant comment on rynns world though!) and some of them weren't literary masterpieces by any means, but I knew what I was reading and enjoyed them as nice straight forward reads as much as I enjoy the more complex and "better" written stuff for being much deeper and more immersive.