Their approach of strapping a booster to a plane always seemed misguided to me. If the first step in designing a new rocket is to also design a new airplane, and the largest in the world at that, then I think you are throwing money and engineering time away. You now have _two_ really hard problems to solve instead of one.
But I have to say that after seeing what SpaceX has done I am now much more positive and supportive about moonshot ideas instead of being dismissive. So, at any rate, kudos to Stratolaunch!
The flight of the Roc launch plane is very impressive, but they have a real problem with the rocket. The Pegasus XL is not cost effective and they've dropped the plans for making a custom air-launched rocket. With Paul Allen gone, it seems like they're trouble unless they can find another backer with deep pockets.
But I have to say that after seeing what SpaceX has done I am now much more positive and supportive about moonshot ideas instead of being dismissive. So, at any rate, kudos to Stratolaunch!