Adam Nimoy began work on For the Love of Spock while his father was still alive and the film indeed features some footage of and narration by Leonard Nimoy. However, the film as a whole turns out to be an epitaph of Nimoy's career, covering his life before and after Star Trek. There is also a particular focus on Leonard's personal relationship with Adam, which had many ups and downs over the years, including a full-on estrangement in the mid-2000s. The film also features interviews with the entire surviving original series cast, as well as the cast of J.J. Abrams' Star Trek reboot (along with Jason Alexander for some reason).
There is probably not much new that a hardcore Star Trek fan is going to learn about Leonard Nimoy while watching For the Love of Spock. However, the film does feature some interesting pieces of trivia, such as the origins of the Vulcan greeting. Overall, For the Love of Spock is a wonderful and emotional tribute to Leonard Nimoy and his most famous character.