One thing that always strikes me upon reading Boswell's biography is Johnson's character in early childhood. Not only is he so opinioned as a child that he persists in attending church on his father's shoulders, or so the story goes, but he is so assertive (one might say brutal, perhaps at least to women?) that he actually beats his school mistress for following him protectively at a distance. One doesn't wonder that as a man he was bold enough to make the criticisms he did, such as, for example, of Shakespeare and to Fanny Burney.
My impression of Dr. Johnson is derived entirely from reading the excellent biography by his friend James Boswell. Johnson was an exceptionally intelligent and gifted man but an uncouth character who had bad manners and an unsightly personal appearance. Boswell makes his biography interesting by filling it with anecdotal material which he was able to get because he enjoyed a close personal relationship with the older man for many years. Boswell also quotes verbatim from Johnson about his life, his friendships and enmities, and his opinions about literature and many other topics. Reading Boswell's Life of Dr. Johnson is a great learning experience about the period and all sorts of intellectual subjects. Johnson's character also provides a great deal of humor, which spices the biography. Boswell himself comes across as a humble hero-worshipper but a very likeable person as well as a clever writer. Johnson is especially admirable because he was the first English writer to make a living entirely from his own writing and not from being subsidized by any patron. His "Letter to Lord Chesterfield" rejecting Chesterfield's patronage is a masterpiece and a sort of literary declaration of independence. It is quoted in full in Boswell's biography and the incident is described in detail. Johnson was an extravert who knew everybody in the English literary world and was admired by most of them.