More of the Same
Like Mein Kampf, this book provides insight into the mind and politics of history's greatest villain. Also like Mein Kampf, it shows how much Hitler appreciated the idea of repetition. If you repeat a lie often enough, it becomes the truth.
This is less a book than a treatise on the specific question of South Tyrol in the 1920's. It is almost entirely devoted to this single question and Hitler's attempts to change the opinions of the majority of Germans, including the Nazi party. While Mein Kampf covered many topics and had some interesting historical anecdotes, the Second Book covers one topic and it isn't even a particularly interesting one.
One good thing: the anti-semitism from the first book is toned down quite a bit in the second. It's still there, but without the foaming at the mouth rhetoric.