The one thing I really agree with Shatner on, is that in most of the original series episodes the crew was faced with an ethical dilemma. Often the dilemma didn't have an easy answer, or it wasn't always clear what was the right thing to do. They always made you think about what you would do in a similar situation. In Star Wars, there's a good guy and a bad guy, and you root for the good guy. Trek was more "intelligent" in that respect.
That was what often disappointed me about the later series'. They tended to not incorporate such ethical dilemmas that seemed the cornerstone of the original series.