I think they can look very smart, but it depends where you are. If you live in a town with windows close to the road/footpath, they're a stylish way of letting light in but preventing people being nosy.
Where I live you're hard pushed to see the windows from the road. We don't even draw the curtains most of the time but enjoy an unobstructed view of the hills across the valley.
I wouldn't have them here, but would consider them if I lived where I might be overlooked. I'd be concerned, too, about them keeping the light out - I can't see the point of having lots of natural light and then shutting it out. However, the previous posts suggest that white shutter can help to brighten the room so that makes them seem much more attractive.