For me, the preference is definitely to build the characters in my own mind's eye as I read. It may not be as detailed and certainly may not match the author's vision, but that's how I roll. I'm certain there are exceptions which I do not recall, but I'm drawing that line in the sand (interesting that one draws a line in the sand, a line which even the smallest of children can change). And yes, I still read a book with detailed character images on the cover, but I don't "use" them when I read!
As to status of "The Storm Drain Chronicles: Enter the Storm Drain", I'm waiting for review notes from my Alpha reader on Part I (Prologue, several "mini chapters" and chapters 1-5) and working on revising Part II, still focusing on trimming the fat.
Onward, ever onward.