The battle on the planet Kashyyk did not seen very relevant to the actual storyline. There was a battle with wookies with some new design looking imperial scouts, but what was the really point of that battle? All that is said is that "Oh the wookie world is under attack, we can not afford to lose that system" . There were attacks everywhere, so what was so important. maybe perhaps the book explained more which I have not read. Yoda was sent there which kept him busy, and said goodbye to Chewbacca, Yoda will always remember him. I get the feeling that there was no real point, but only to have wookies in the movie. Any comments?
I looked at Kashyyyk as being yet another planet that was in the midst of the war. I liked how it gave Yoda some "field time" of his own...I feel it gave his role as a leader more resonance.
I also though it was pretty cool seeing Scout Troopers in action once again. It wasn't all about seeing Chewbacca.