Half way there
Twin fuselages make for a clean payload space without massive undercarriage. The split tail removes any risk of interference or contact if the payload gets mardy, either before or during launch. It's becoming a classic configuration for space launchers. ISTR Rutan has retired from Scaled Composites, nevertheless I find the most surprising thing about this ship to be how conventional it is in other respects.
Main problem is that nobody has yet built a sensible orbiter on this scale that can launch horizontally: the structural, and hence weight, penalties of turning a coke can on its side are surprisingly large. If this beast finds a customer to do it justice, that will be the real breakthrough.