I played it for a short time tonight and noticed two things - the sound is improved and for the first time I have heard the horses galloping into battle - very exciting. But. also for the first time, I played in windowed mode and each time I resized the window the sky and lighting changed. I saw grey, deep blue, cloudy, sunset - every kind of sky for each 1mm movement of the window. I am not sure if this is a bug or a brand new "choose your weather" feature.
My graphics card is Nvida 9600 GT and I have 4gb RAM.