A garage door window is something that you will have to consider when purchasing a new garage door. There are both pros and cons to purchasing a garage door with a window in it.
Before anything else is considered, you will need to find out if the local housing code even allows for a garage door window. Codes in some low lying hurricane areas don't allow garage doors with windows, making your decision for you.
If you are concerned about theft in your area, or even nosy neighbors, then a garage door window is definitely something you will want to avoid. The main disadvantage of a window in your garage door is that, depending on the height and size of the window, there may not be any privacy offered.
The main advantage of having a garage door window, besides added curb appeal, is lighting. If you spend a lot of time in your garage but don't want to have the door open, or rely on artificial light, then strategically placed windows will light up your garage, allowing you to see better.