I read The New Voyages (1976—Sondra Marshak and Myrna Culbreath, ed.) short story anthology, and I would say it was quite enjoyable. Surprisingly, the authors are all women. A good majority of the stories are focused on Mr. Spock, but Kirk and McCoy are also prominent. The short story format really suits Star Trek, to me. Reading this anthology is like reading a lot of older pulp science fiction—zippy, daring, and imaginative.
Intros by Roddenberry and the cast are as you’d expect—celebratory, kind, too much of them, no real anecdotes or wisdom of note. Still, in sum, they provide an interesting snapshot of how the Star Trek phenomenon appeared to them at the time, and they lend the stories a degree of authentication.
I think Marshak and Culbreath did a good job curating the best of fanfic of the time. The stories are almost all lovable and memorable. Some of the authors complained that their stories were cut down, but I suspect these changes were probably for the best.