Functional and adequate to you is a zero? John Byrne is functional and adequate and I wouldn't even rate him a zero, though my personal desire would be to do so without hesitation.
The art did nothing more than illustrate the story. Looking at someone like JH Williams or Skottie Young whose art has masses of character and adds something to the writing be it atmosphere, be it cheeky background moments or even just a creative layout it adds to and improves the comic so I'd give it some points.
On the other hand you have someone like Rob Liefield whose art detracts from a story. Put this guy on an issue of even my favourite comic and his work would put me off and lessen my enjoyment so I'd probably score it lower.
With Ivan Reis (or Tom Raney or Mark Bagley or any of the artists on 52) the art just tells the story. No bells, no whistles no impact. It neither adds to nor subtracts from the story and merely sits there. Ivan Reis is an artist neither added nor subtracted from my score because honestly one of a dozen people working in comics today could have done the exact same job.
I did read it though. I read it twice to make sure I genuinely hadn't understood what was going on or why. Even when I don't post reviews I always try and read the comic in question. I've even been surprised. Superboy #1 and Heroes for Hire #something both won me over despite not interesting me in the least. I always have an open mind when reading these books but time and time again Geoff Johns has written comics that are everything I dislike about the superhero genre and written them poorly.
BN #23 probably won't get an overall average of a zero because there are people who can find something in its pages that they'll like. Not me. I honestly found nothing about the book to recommend it so dished out my second zero in a row. I note no-one complained about it last week.