The feature film Star Trek: Generations was a bit disappointing to most. But then, I don't think there is any "right" way to kill off Captain Kirk. However, the movie - although not horrible - still left a lot to be desired. The book, however, fills in the gaps very nicely.
The most noticeable being all the scenes that the author added - that took place even before the movie started. It added much needed character development.
It showed nicely how Kirk was a depressed person after his crew was disbanded. It even had a few scenes with Kirk talking to McCoy and Spock. It had a scene of Sulu's reaction when Kirk first "dies". And most importantly, it added a scene of Kirk's first encounter with the Nexus, before Picard asks for his help. Many people probably wonder why the great Captain Kirk wasn't so eager to help Picard at first. This book answers the question, and makes the movie even more understandable.
Therefore, it is worth reading.