Shmoop - Narrative of the Life of Frederick Douglass, An American Slave. Written by Himself.

The full title of this book is Narrative of the Life of Frederick Douglass, An American Slave. Written by Himself. Pretty straightforward title, right? Frederick Douglass was a slave, and this is going to be the narrative, or story, of his life. Well, that's what it is, and sometimes straightforward is good.
But there are also a couple things worth noticing here. First, by calling himself an American slave, Douglass is reminding his audience that slavery didn't happen in some faraway land; it happened in America, the "land of the free." We're supposed to notice that and think about it. Douglass loves this kind of irony, and reminding us that the land of the free is also the land of slavery is just the kind of hypocrisy he likes to point out. (Years later he gave a famous speech entitled "What to the Slave is the Fourth of July?" which you can read here.)
The second thing is the phrase "Written by Himself." That might seem basic, too, but there's a serious point there. Most white Americans in the mid-1880s had a hard time believing that a black person could even learn to read, much less write a book. In fact, when the book became a bestseller, there were a lot of skeptics who insisted that he must have had help. This is why Douglass included two different prefaces from famous writers at the beginning, to sort of vouch for the fact that he did it all on his own. Just the fact that he wrote the book by himself was a way of proving that black people were the equal of whites.

The ending isn't really a surprise. You must have figured out that the book would end with Douglass getting his freedom, right? Plus, even if you didn't, Garrison's preface gives it away. So it's not like the "getting free" part is the big climax.
Instead, the ending challenges us to think about what "freedom" really means. Douglass wants us to understand that slavery is wrong and should be abolished, of course, but he also wants to show that freedom is something more than a legal category. For one thing, even when Douglass does get his freedom and goes to New York, he's lost and alone. Without the help of his friends, he wouldn't have been able to make a new start.
Even more than that, though, Douglass's real triumph is in finding his voice, both as a public speaker and as an author. We think that's why the book ends by returning to the moment that Garrison talks about in the preface, when Douglass first stands up and begins telling the crowd about his experiences.
In a way, the real happy ending might just be the fact that the book you're reading exists at all. After all, Douglass tells us that at first he didn't want to stand up in front of a crowd of assembled white people because he still, on the inside, felt like a slave. And just as giving that speech shows that he's finally become free on the inside, the fact that he follows it up by writing this book makes the same point: after freeing his body, becoming an author shows that he has freed his mind. Yet this also suggests that getting his freedom hasn't really been the end of his journey.
In fact, getting his freedom is almost anti-climactic, since slavery continues. Getting his freedom is in a way the beginning of Douglass's story, the beginning of his life as an activist working to end slavery and the beginning of the long road to freedom that African-Americans have traveled ever since.

Although Douglass's language may seem a bit stilted to us today, his style is usually pretty straightforward. He wants you to understand him, so he doesn't write long or complicated sentences, and he tries to speak informally, as if it were just you and him.
Still, he does sometimes use a kind of elevated language, and parts of the book can be a bit difficult. It might be that he's emulating the style of the King James Bible, one book that almost all of his readers would be familiar with. And he also might be showing off a little, since he had to fight so hard to learn how to read and write.
For example, this is how he describes Aunt Hester being whipped:
I remember the first time I ever witnessed this horrible exhibition. I was quite a child, but I well remember it. I never shall forget it whilst I remember any thing. It was the first of a long series of such outrages, of which I was doomed to be a witness and a participant. It struck me with awful force. It was the blood-stained gate, the entrance to the hell of slavery, through which I was about to pass. It was a most terrible spectacle. I wish I could commit to paper the feelings with which I beheld it.