uh.... that's too big a question for me to answer. I loved the entire movie. But all Kirk and Spock interactions are perfect. I loved it when Kirk sees Spock swimming. That was hilarious! And I love Scotty's "Computer? Oh a keyboard, how quaint." And Spock and Kirk's Italian conversation. Hell, I even like nuclear wessels.
Nimoy did an outstanding job on this film. We forget what a good director he is and how well he understood Star Trek. He is the most intellectual, and perceptive of the original cast and it shows in this movie and in his comments regarding the other films.
Voyage Home is a wonderful movie. It's completely re-watchable.