More than deserving of its acclaim as one of the best of classic Sci-fi. 
 The book is a complex examination of human nature, set to the backdrop of undated future earth after two alien invasion attempts. Population control is enforced, and the grip of governments and their military is tight, even in the freer countries. The ethical implications of such a world are thought provoking and abundant. (I for one lost count of how many times I asked myself:' Do the ends really justify the means?') The cast of characters are vibrant and memorable. The author's grasp on depicting complicated action sequences was impressive, though I would have enjoyed a little more strength in the use of physical descriptions. 
 The author's greatest achievement, in this reader's mind, was the steady build of empathy he managed to develop. I truly ached for young Ender and many of these children as they were being groomed into military tools. While I don't know that these children could have realistically thrived at all under deliberate conditions of isolation, devoid of love or security, it did thoroughly outline--or perhaps forewarn--how far 'civilized' governments would likely be willing to go in the name of self-preservation. 
 The political intricacies were an inspired additional layer to the world-building, deep enough to be believable without bogging one down in needless detail. That, along with the deft emotional immersion, managed to make the book feel timeless in spite of the year it was written.