It's a depressing book because the human characters are convinced (correctly, and convincingly) that this is normal. They have some leverage (our protagonist hacks RFID microbes so that his friends can circumvent a few rules) but they don't think of themselves as an "alien resistance movement"; they're just humans who have avoided being killed (or mind-controlled, or randomly cyborged, or melted or whatever). They speak an alien-punctuated argot. They don't even think of Earth as their planet. They know they are "indigenes", but to most of them it's just a word, generally found in sentences like "You are not cleared to be outside the Indigenous Population Preserve after curfew."
So after all this is introduced, their terrible life gets worse; some faction of aliens has gone from violent indifference to plain old violence, and flying saucers are razing the human IPPs. Behold! Rumors of a far-off place where humans live in safety! The scrabbulous petty gangs of the city attempt to join up and migrate. In the meantime, a mysterious stranger is the destined...
This is about where the story goes off the rails. Phrases like "destined" and "mysterious quality of the human soul" start popping up. We eventually learn a little more about this world's history, but it anti-explains things; the book gets less plausible the farther it goes. The ultimate gimmick (there is an ultimate gimmick) is cute; I mean, I liked the idea and I see why the author wanted to write a book underneath it. I would probably have been impressed, way back when I was a teenager trying to find obscure Ann Maxwell novels. At this point, however, the grim-dark squalor is not shocking and the metaphysical gallimaufrey is not convincing, so I did not buy into the plot. This is a pity because it's really well-written.