It would add interest to that wall. I have a wall that is similar but a little smaller and I put a framed picture in mine. But my room isn't as high contrast as yours, so you could easily do iron.

Maybe first find a better window treatment that looks like a shower curtain on the window. I have no idea why iron would be a good wall decor without seeing the whole space but usually a piece of art with some color is a nice choice in bathrooms