What are the positive and negative effects of urban sprawl?

Firstly, in your answer it is always good to start with the definition of the key word being asked about.
So what is Urban Sprawl?
Urban sprawl is literally the spread of urban areas into low-density areas.
The positive effects are that people can move companies into less-competitive areas. In addition, people can have more accessibility to airports and motor ways (particularly important for those who travel long distances for work). Also, very often land in low-density areas tends to be cheaper, so new or up and coming businesses can benefit greatly from this reduced cost.
The negative effects can be mostly linked to the environment. Obviously. urban sprawl encourages the degradation of agriculture. Also, it increases pollution and congestion in rural-urban fringe areas. Less likely but also applicable, it can also damage habitats and have a negative effect on habitat production and the maintenance of eco-systems.
In an answer such as this, it would be very useful to use a case-study. This would of course be dependent on the student and what case-studies they have been exposed to.