This story is the inspiration for the musical "The King and I" and its various film adaptations. I have to say, Rogers and Hammerstein have a better eye than me. The book was sort of... excruciating? Okay, more detail to follow, but the short version is: Rent the movie.
As is wont to happen in a memoir, the author has a certain perspective of herself that she tries to get across. Less concern is given to story-telling and more is given to the emotional impact of the author's own experiences. In this case, the book is some combination of a travel log, a history textbook and a memoir. The travel log was unexpected, and Leonowens dedicates long chapters to her trip to and from Siam. Given that there is no plot or character development in these portions, I found them quite dull. The description of the landscape and ruins has some great imagery, but without context it falls flat.
Leonowens, possibly as a teacher with an interest in history herself, includes long passages following the important events of Siam through several hundred years of rule, including some of the personal exploits of the King's ancestors. Mostly, this section is really dry, reminiscent of my middle school textbooks. Since this is all presented before the King or his court are introduced, my interest level was zero and I skimmed through this really quickly.
Finally, there was the memoir. Leonowens is somewhere between ethnocentric and xenophobic and a lot of the more personal stories she tells involve her being terrified and afraid for her life. She seems to be trying to garner some empathy for her difficult situation. She also emphasizes her deep love for her students, though she barely mentions her time in the classroom and only talks about two in particular (one a princess and the favorite of the King). In her interactions with the King she seems to view him as a petulant child in need of scolding and she has little respect for the traditions and culture of Siam. When she finally leaves she seems bitter and it is difficult to tell if she enjoyed any of her time in Siam. Whatever heroic, brave, tolerant picture she tried to paint of herself failed. I found her judgemental, superior, and certainly not a savvy traveler of the Orient or an early feminist.
Pass on this one.