Finished the book today. Wow I didn't know about the ending... Ok Silver, here we go

SPOILER AHEAD

Ok before the very end I must say the final sequences are in slightly a different order. First the robots stop the chase because overbudget, then THX reaches the super-structure where furry "cavemen" attack him... and finally he goes up the ladder leading out (not before breaking through a rusty grid though).

After THX emerges from the shaft he basically sees a paradise, grass on the ground, birds in the sky, a river nearby, warm sun. From the river eight people wave at him inviting him to come closer. THX looks back and thinks they are all mad to live in there and promise himself never to go back... except once to save LUH (his child).

The very happy ending kinda relieves from the depression of LUH's tragic destiny. It would have been much worse if it ended the way Lucas initially thought (with a radiation wasteland awaiting THX)... thank God for that bird passing in the shot!

Now we wonder... were those people at the river other escapees from the underground city? Or have they always lived there and no nuclear holocaust ever happened? Open questions always make sci-fi books more interesting.

PS on a different note, I find incredible that even from the book it's not clear whether SRT is a real hologram or is an actor from the holoshow. The words they used were as ambiguous as in the movie.