Not unlike Trump, he is not perfect.
However, he has an 80% New American Freedom Index rating which is respectable because it uses stringent criteria. He has a 93% Heritage Action score. (By comparison, Rand Paul is at 94%). I was unable to locate a Conservative Review score.
These are good numbers for a Republican.
But more importantly, this selection makes Trump less of a target, because his opponents would then get Vance. And in four years, Trump would be perhaps followed by someone who would continue and build upon his legacy and his priorities. Trump needs to be less concerned he will be stabbed in the back.
Very importantly, Vance communicates very well, unlike many other Republicans; and he seems to be a fighter. Overall, I think this is a good pick for Trump. The media/left complex will go bananas, but they will do this no matter whom he chooses.