From a personal point of view I think this is a good move. They were never a favourite of mine and the are going to look a tad weak against the Marvel characters:
http://www.disnology.com/2010/05/13/the-walt-disney-company-no-longer-owns-the-power-rangers/
http://www.disnology.com/2010/05/13/the-walt-disney-company-no-longer-owns-the-power-rangers/