As Roger Moorhouse notes in the book's introduction, this book shows Hitler as his inner circle saw him, not as a political extremist, but as a man. In that sense, Hitler is shown as a person who could inspire loyalty and affection, characterized by being a charming person with his closest collaborators.
The book consists of 180 pages, but the memoir are just 90 pages. So, it's a very short account, mainly focused on the last period of Hitler's life.
In general, the book isn't so interesting. I think the writer doesn't tell us anything new. Most of the information provided about the historical events are well known. So, the only worthy from his memoir would be his anecdotes with Hitler. However, they don't contribute with anything new about Hitler's personality in his private life. I think that the memoir of Traudl Jungle and Christa Schroeder (Hitler's secretaries) are most interesting to approach to the most intimate side of Hitler. Also, Heinz Linge's memoir (Hitler's valet) provides a better account of that aspect of Hitler's life.
If you are interested about the most personal side of the nazi dictator, I would recommend you buying any of the aforesaid memoir. Don't bother buying Kempka's memoir.