More efficient lighting. Halogen bulbs waste about 80% of their energy by generating excess heat, LED's only waste 20%.
Better light quality. LED's provide a much clearer, crisper quality of light.
Better investment. The average halogen light will last about 5000 hours. LED's can last up to 11 years or more! The money you would be spending on installation and new bulbs can now be spent on more exciting things!