I think he is well-regarded by academics, though he writes for a popular audience and so takes some liberties. When it comes down to dry fact and lack of evidence, he will usually opt for the more dramatic or fanciful interpretation. In this way he is a lot like Plutarch (and I hope he does not see this and get offended!). He needs to sell books, after all. Here is a review of his Alexander Hamilton biography, which has some nice things to say. Scroll down to bottom of page 7 in the pdf.