I think they're what they say they are: benevolent in their own way, and want us to join their alliance. From all of the contactee things surrounding them, they seem to view us as part of their family. You can take that however you see it, I guess.
Reptilian/Greys are Gay Niggers from Outer Space and clearly working with the evilfags here on Earth for whatever purpose. My guess, which is as good as any, is they want to turn us into their slave race, and have promised their earthy allies the works to get it.