I think I would have to read this a second time to truly understand it. Or maybe this is the kind of book where you just don't "get it", that's the point. In all honesty, I had been looking forward to reading this for so long that I came away slightly underwhelmed. That's not to say I didn't enjoy it, because I did immensely, but I didn't think it was the PKD masterpiece everyone else seems to. I preferred Ubik and A Scanner Darkly. Maybe after a re-read a few years down the line my opinion will change.
This is definitely one of those twisty-turny rambling novels that will pulverize your brain and cause you to question the nature of reality. Written late in Dick's life, after he had renounced drugs and started experimenting with God instead, this semi-autobiographical story relates the religious experience of Horselover Fat (who is really PKD's alter-ego after he had a psychotic break following his friend's suicide), who saw a beam of pink light that he referred to as Zebra (later VALIS) and it transmitted information to him that helped him save his dying son, who he didn't even know was sick. Yeah. And then there's some stuff about ancient Christians and double helixes and crazy rock star filmmakers and AIs inside of little girls. See why I might need a re-read?
Oh PKD, you so crazy.