Pretty solid! Only minor issues I could spot were:
1. Wrong carrier for my mobile - number started out life with a UK MVNO (sainsbury's mobile), I have since ported it to Virgin UK (another MVNO) but Twillio lists the carrier as being EE (which is sort of correct in so much as that's who Virgin resell capacity from).
2. No carrier type info for UK voip numbers - tried two numbers, one from Telappliant and one from Andrews & Arnold, got nulls back each time :(