Looks good. There was a version I think of Justice League which was in b/w, but I'd love to see a Batman movie which is fully shot with non-colour film. It'd truly force the director and cinematographer to use all the classic tricks in the book to bring out the strengths of black and white film. Psycho, The Maltese Falcon and Casablanca all look absolutely gorgeous and have a thick atmosphere you can cut with a knife.
I hope the showrunner has gone to great lengths to make the b/w version the ultimate one and not just a gimmick.
Edit: I watched the color version and it looks too good. With a singular b/w vIsion the sets can be filmed with the strangest real life colors just because they look so much better in b/w.
Here's what George Reeve's suit looked like with its actual colors in the show:
I think this is what is lost in this show. Ah well, at least they'll likely have put some thought into it and made it as good as they possibly could under the mandate of Bezos.