I'm also not a fan. As a piece of juvenile science fiction I think it's serviceable though if I had children I'd probably prefer they skip it.

To start with, the story is predicated on the notion that Eugenics works, or as the saying goes; if it's not outright saying it, it's sure implying it loudly. It's reasonable to say that two intelligent people will probably have intelligent kids, but the novel goes way past that. The three children are freakishly (in the novel's terms, this is another one of my gripes I'll get to) intelligent.

It's not something that could be accomplished without an extremely long and large breeding program, if at all. (also note, you'd be producing an awful lot of pretty freaking smart kids, see my next point) It would mostly be a matter of luck and at that point why have a breeding program at all? Therefore the intelligence of the children is strongly implied to be a result of the breeding program.

In terms of artistic objections, the "freakish intelligence" of the children is accomplished by making most of the other characters in the novel cardboard cutouts or strawmen that Ender can just knock over or tear apart easily. What happened to all the other kids from the breeding program? Surely it produced a bunch of "90% Enders" who are almost as good. It comes off as contrived and inauthentic.

The whole "child soldier" angle is ridiculous as well. Child soldiers are used in conflicts because they are easily manipulated and readily available but that is not always desirable. A rebel fighter in Africa only needs someone who can hold and point a machine gun to replace the last guy who was doing it. The needs of the military in Ender's Game are quite a bit more sophisticated.

Children are also ignorant and dumb. Innate intelligence can only take you so far, it gives you a large "gas tank" but you still need to fill it with gas.

Military Strategy is not necessarily a terribly intelligence-taxing thing. It's mostly a question of learning from the past, taking into account current technology, and trying to anticipate other attacks. If they really wanted to win the war they'd put an experienced General in charge of strategy and have Ender start working on the next great super-weapon, that's what makes decisive victories.

The whole "the enemy's gate is down" thing is a good example of how Ender is not smart, everyone else is dumb and also how the book has a flawed view of military strategy. The "the enemy's gate is down" is a lesson we learned hundreds of years ago at the latest (i.e. the transition from neatly lined up soldiers standing in rows across from each-other firring muskets to modern trench and guerrilla warfare). Is this some bizarre future where we've forgotten all the basic lessons of military history for the past thousand years? Or is this just the worst military academy ever?

Going back to Eugenics, the book's plot requires that Ender is so intelligent that it's more efficient/effective to try and train him up to a brilliant strategist than to just use one of the existing ones. I don't find that realistic.

I also don't buy the whole "He's a kid so he'll look at it from a fresh angle" aspect. Sure kids do tend to be a bit open minded but I find it dubious that they would naturally have the right kind of open mindedness for this application, that is an informed one.

I don't care how new the MD Device is, we're to believe that they have no idea how it works? Not even a guess as to what would happen if you fired it at a planet? Come on... nobody said "let's shoot it at an asteroid or something"? When nuclear weapons were developed pretty much right away nuclear scientists stood around like excited schoolgirls with a puppy coming up with all the super neato places they could set off an A-bomb to see what happens (Underwater! Space! "uninhabited" islands!)

Honestly I could go on and on about all the things I dislike about this book. I realize I might seem a bit worked up, but really it just slightly annoys me that such a mediocre book is so popular. It owes it's popularity mostly to the fact that it's a classic underdog story. A lonely nerdy kid who's smarter than everyone around him kicks ass and chews bubblegum, it's a young sci-fi nerd's wet dream. I know when I was in middle school during tough times I would occasionally spend time daydreaming elaborate revenge fantasies where I showed everyone up, so to a kid like that Ender's Game is very validating. That's good in some ways but I also worry that it can be unhealthy because I think while that sort of mentality is natural is something that needs to be overcome and not indulged.

Overall I find parts of it unwholesome and overall offensive aesthetically.