This was an eye-opener for me as I knew very little on Spain's American territories, besides brief descriptions of some of the conquistadors such as Cortes and Pizzarro. What Elliott has done in this book is to show the comparisons and contrasts between England's New World Colonies and Spain's. There are many fascinating facets underlaying the reasons for acquiring these territories, how both sides viewed their mission and goals, and how they governed them. This is without a doubt a remarkable book that revealed a lot for me.
The first colonization was begun by the Spanish in the early 16th Century. The English made their first successful attempt in the early 17th Century. Both South and North America posed different challenges for both governments, i.e. the size of the indigenous populations, the geography and climate, natural resources and so forth. For me, the real fascination was learning more about the Spanish colonies and the establishment of the viceroyalties of New Spain (based in Mexico City) and Peru (based in Lima) with additional ones developing over time. The interaction with the natives, the attempts at Christianization, trade, and many other aspects of Spain's colonization were quite enlightening.
Being more familiar with United States history, I felt more familiar with the material covered on England's planting of settlers in Jamestown and later in New England. However, the real education was in Elliott's efforts to show how each of these two powers (Spain and England) confronted the realities and challenges of establishing their presence in these very different regions. The differences were often quite stark. Some of the points of contrast that most differentiated the two powers included each nation's attitude towards the Indians (including the attempts or lack of evangelization) and the extent of imperial bureaucracy brought over from the mother countries.
Elliott also describes how world events had helped to shape and or guide the developments that occurred in both country's territories. The Reformation, the British Commonwealth under Cromwell, the Restoration, the Glorious Revolution, the French and Indian War, the French Revolution and so forth, all served as factors in shaping the events that transpired in North and South America. The role of various monarchs, religious, military and political leaders, as well as indigenous leaders, are also discussed.
Elliott does try to take an even-handed approach in acknowledging the strengths and weaknesses of both government's endeavors. Of course it goes without saying that the notion of empire, with the connotations of exploitation of natives and their cultures, is unpopular in most peoples minds nowadays. Yes, it was and remains a blot on the records of all nations that engaged in replacing the livelihoods and cultures (sometimes more like extermination) of indigenous peoples, or those who engaged in the slave trade, but we must keep in mind that we have to try to keep modern standards in check for historical purposes.
This is such a broad subject that I find it hard to even begin to touch on more specific details found in this book; I'm just trying to outline the broader contours of Elliott's book. Having some introduction to this time period will help you, but you need not be an expert on this particular topic. An illuminating read.