What did I think of it? Well... read on.
In a nutshell, the story is of a Japanese 3rd year middle-school class of 42 students' struggle... to kill each other. In this alternate history world, Japan is part of the Republic of Greater East Asia (it's implied that the Japanese Empire successfully conquered China and Korea in the early 20th century and World War II either never happened or Japan was not involved. At some point, the emperor was replaced by a puppet figure called "The Great Dictator", while the country is actually controlled by an inner council) and for decades, random classes of 3rd year middle-school kids have been chosen for "The Program", in which the students must battle for survival until only one survives - or else all will be killed.
Why? There's no real, obvious purpose to it. Unlike the later, American, series HUNGER GAMES, the Program isn't televised and not much of a big deal is even made about the winners. So what's the purpose, everyone wonders while hoping they or their children aren't chosen.
The story is described as fast-paced and thrilling and it may well be in the original Japanese. Unfortunately, this book suffers from an ailment many novels originally published in Japanese suffer: a god awful translation. The translation isn't quite a straight transliteration, but it's not far from it. The translator wasn't much of a writer and doesn't seem to have been as familiar with the English language as might have been desired. Because of that, and its length (the book is nearly 200,000 words), it can be a struggle to get through.
Viz, the publisher, apparently realized this and later released a completely different translated edition. I wish I'd known that before buying this, but hindsight is 20/20 and I did find it at a used bookstore, so at least I didn't pay cover-price.
As for the story itself, it's okay. I originally started reading the manga adaptation of this novel, but stopped after the first volume because I hated the art. That may also have been a mistake. This novel was Takami's first, and only, and the story is rather one-dimensional, as are the characters. The manga, which he also wrote, supposedly has much better developed characters (the guiding hand of a good editor is probably at play there), and may be worth checking out, despite the art.
That being said, some of the individual scenes in the novel are great. As you may already suspect, the novel is basically a long string of fight/chase/murder scenes strung together with some background and linking material (a good deal of which isn't really necessary). Some of these scenes, particularly a running gun-battle late in the novel, are quite good. Takami, if nothing else, has a talent for fight choreography, something that can be difficult to attain in prose.
I don't regret reading this novel, but I do wish I'd read the newer translation, so if it's something that interests you at all, I suggest you seek that version out and give a pass to the original English edition.