I wrote a roundoup of articles explaining why carousels are bad and kill clickthrus earlier. Jakob Nielsen provides some advice on how to design one properly if you really must have one.
Summary: Carousels allow multiple pieces of content to occupy a single, coveted space. This may placate corporate infighting, but on large- or small-view ports, people often scroll past carousels. A static hero or integrating content in the UI may be better solutions. But if a carousel is your hero, good navigation and content can help make it effective.