It's a great place to add a featured design element such as a lighting fixture that is decorative as well as useful. In addition, a lighting fixture adds dimension to the space, adding spacial perspective to this featured area. A pendant can function as an element that is a further connection of the kitchen style or that can nudge the style in one direction or another via color, finish, or style. A ceiling light or recessed fixture contributes to the design by reducing decorative clutter, allowing the eye to flow around the space with fewer visual interruptions.
Depends on if you already have pendants hanging in the area. You do not want to distract from island pendants, but if you can find a slightly different proportioned fixture, I love hanging fixtures at the sink. I like to make sure that all my lighting compliments each one another! You do not want to create a distraction, a busy environment!