If I were a guy, or younger, or at least less feminist inclined, I probably would have liked this book a lot more.
The Forever War is incredibly dated. It's not just old ("old" sci fi, even with dates we have already lived through isn't necessarily dated), but feels dated and almost irrelevant.
It is heavily influenced by the Vietnam War, which the author took part in, and it's almost the Vietnam War In Space. The war lasts forever, it was pointless, lots of good people and resources are wasted. In the end a "peace" is declared, but the war is never won, and you don't get the satisfaction of anyone "beating" anyone else.
The main character, William Mandella, is drafted (along with many others) because he has a high IQ, into the military for training and to be shipped out to fight aliens which have attacked humans, and are seen as a threat.
Due to time dilation effects, the war is sloppy and slow. It takes years for the military to get anywhere (and back home, and back out again), so Mandella ages normally while time flies by. After his first tour, he comes home to an Earth society drastically changed, only to re-enlist and get trapped into another tour. He again comes back to another time, a different society, and this cycle happens repeatedly. In the end, he gets a "happily ever after" ending, which I would have enjoyed more if the author had cut it shorter (his companion, who has been with him through all of these time dilation effects, has chosen to use spaceflight and relativistic effects to 'wait' for him to come back to her).
Several things were very good about this book. While I'm too young for the Vietnam war, I grew up with family and around those that were involved, and many of the things/feelings/over-arching situations in the book rang true.
Unfortunately, the author's bizarre focus on sexuality (and homosexuality) in particular were just odd and felt forced. While there is an interesting (and enlightened) take on the forces that society can place on what it considers "normative" behavior is awesome, the fact that he makes state sponsored rape A-OK doesn't sit well with me (women were required by law to give in to sexual advances, at least in the military).
In the end, it's always good to read an award winning book, but I was thankful and happy it was relatively short and a quick read.