I know I really appreciate art, and like it in the story (as long as it's illustrating a scene, I guess), but I do have to go and look at art masterposts separately to comment as they deserve, and by separately, I mean once a week, not right after reading the story.
I think it's an extra task to match the mood of the story with the mood of the art (one I think I achieved with my first one, even though I think the quality of the art in the upcoming second one is better). Hell. I can't match the mood of all the pictures...
Anyway, if the pictures are properly fairy tale storylike (there was one of Cas as a dragon that did it really well, by the time I get to a masterpost, I forget that characteristic.
The failings are all on me, as a commenter. As a consumer, art with pictures is unquestionably the best. PMM and my author are on crack. Unless all the choices of scenes to illustrate stood out as memorably to the reader, there's a level of ??? when going back and looking at pics, especially if there are a lot.
Since I just decided to give her one picture per chapter (just one left to decide on), some are bound to be confusing when viewed in isolation from the narrative. But that's me and the author's requirements. I hope to quote enough text to help bring the moment back.
My method of working is to print out the fic, read the hard copy (why??? It's the only time I read hard copy....) draw the picture, print it out and stuff it in the right place in the stack, and move on.
But I also stick the pictures in the electronic copy for my own viewing pleasure--the first author took that copy as her posting copy and posted stories inline. Which I think was even more important for that story than this one.