For someone who has already read a considerable amount of Kierkegaard's works, his thesis was quite the disappointment.
As most academic pieces, it takes too long to touch on the subjects it is actually going to talk about; in fact, that happens only on the second and final part of the book, which is roughly 1/3 of it. The rest is some tedious philosophy history, a recollection of Socrates' life.
However, when Kierkegaard the thinker does come in, on the second part, it shines. Many of the subjects he would discuss in greater detail later on his career might already be seen here, summarised: his appraisal of existence, the steps taken from the aesthetic to the ethic and then to the religious life, the despair and its relation to faith.
It may be a good introduction to his philosophy, but definitely not a book for those already familiar with it. Ironic, I know. Like a free ride, when you've already paid.