The way of the Pilgrim by Dickson is one of the few really good alien invasion stories I have read. It takes place years after the invasion is over. We were against an alien force VERY far beyond us, we were not able to put up any real fight (Think Aztecs verses the US marines of today).
There are two things that really make it stand out, the first the aliens are not just a little ahead of us. They are so far ahead of us that it could very well be possible for one of them with their weapons and gear to defeat the entire military might of the Earth by themselves with little effort.
This is a much more likely scenario then aliens attacking who are far enough ahead to come here, but not so far as to be unable to easily beat us. Think about what a modern air craft carrier could have done during world war two, and that was less then a century ago.
The other thing is that it builds up what would happen to us socially and psychologically during that situation. This is one of the reasons the book is as long as it is, and I feel the page space was well spent. The fact that we do not get a victory through military might or technology makes the ending that much better.