Something about the suit really bothers me on an uncanny valley level. It's too shiny and doesn't bend or move right.
If you mean the Flash suit, I think the cowl looks very weird, something to do with how the shape of it interacts with Miller's jawline and neck shape. It makes it look like a bad CGI render of a costume rather than a physical costume.
I quite liked the Justice League Flash costume, the way it looked like a homemade outfit designed to protect against high velocities.