Kierkegaard scholarship has come a long way since this biography written in the 1940s. Walter Lowrie engages in a ton of highly speculative sleuth work using the pseudonymous works Søren Kierkegaard wrote to spin out fantastical biographical theories. This combined with the prissy reverence with which Lowrie approaches Kierkegaard, makes for a grating experience for anyone who has read almost any other biography on Denmark's most famous 19th century thinker.
Currently the gold standard in Kierkegaard biographies is Joakim Garff's mid 2000s doorstop, but I understand that some people might find Garff's low estimate of Kierkegaard off putting. There are at least two really good short biographies of Kierkegaard that take a more positive (but not sycophantic) approach to his life: Clare Carlisle's "Philosopher of the Heart" and Stephen Backhouse's "Kierkegaard: A Single Life". Either one of these will give you a more up to date and nuanced popular introduction to an absolutely fascinating life. Lowrie's biography is purely of interest as a historical artifact of the early days of Anglo-American Kierkegaard scholarship.