His voice is changing. He has a new repetoire of sounds and baby words. His cries are more distinctive. His facial expressions are all about the eyebrows now.

I do not get the impression that he is a blank slate filling up with stuff. He seems to be working things out, trying to remember, making connections. He behaves less like a new being and more like someone who was gone for a little while and is now back and trying to remember how things work.