[Brookhaven]

The short story is better (imho)—more to the point. The book felt like a short-story that was filled out to make a book.

I believe the author has made the short story available for free on his web site.

[rottndog]

Ender's Game By Orson Scott Card [First appeared in the August 1977 issue of Analog.]

[buwaya]

You are right there.
The guts of it are the best. The remainder is, well, pretty lame really.