It uses practically no energy at all compared to an incandescent bulb and is more efficient than a fluorescent while creating a warmer shade of light than a CFL. It can last 20 years, so you may only change your light bulbs a few times during the course of your life.
The LED is a marvel of energy-efficiency and longevity, consuming about 80 percent less energy than a traditional light bulb and about 5 percent less than a CFL; if you currently use incandescents, switching to LEDs can reduce your carbon footprint by hundreds of pounds per light fixture [source: Layton].
On the downside, an LED bulb can cost from $30 all the way up to $100. It'll save money in the long run, but it's a big expenditure, so it's currently mostly a commercial lighting choice. Prices are coming down, though, so ultra-green LED lighting could soon become a viable green option at home.