Adding dormers to the roof of a house adds a little bit of something to what is otherwise "blah". Not only are they appealing to look at but they offer a little more headroom, light and ventilation into the attic space which is always a good thing.
Things to keep in mind if you plan to install dormers are that the side walls of the dormers must rest on rafters. It is even better to have two rafters side-by-side for the dormer to be placed on.
There are many different styles of dormers to choose from including eyebrow, shutter style, hipped, arched-top and segmented dormers.
I think dormers really make a house look nice, eye-catching. I don't have any on my own house but would like to add some some day.