I now own a 10.5" iPad Pro. I've occasionally used the 12.9" first generation iPad Pro reserved mostly for my kid. The 12.9" is glorious to look at but it was just too big to be my every day device. As expected, the 10.5" is the perfect size for me.
Most of what I've read or heard about the new iPad Pro is close to reality but I think the effect of the new 120 Hz refresh rate of the screen is being over stated. It's nice but it is not dramatically better. It's not even that noticeable. Scrolling looks better, but it's minor. From the early reviews you might expect more but I think there was a lot of pent up excitement for the iPad Pro revision.
The Apple Pencil performance improvement absolutely is noticeable to me. The original iPad Pro and Pencil combination already felt great. Now the line tracks nearly perfectly with the Pencil. I've been using it in Linea and it's a real joy.