This is moving off topic a little bit, but I'm interested in how Lara Parker's novels compare to some of the other instances of actors writing fiction based on their characters. I'm not a big Star Trek fan, but I know that Shatner has had a hand in co-writing some novels based on the series. Are there other instances of this happening? Has there been a case of another actor writing solo about his/her character? How were these efforts received in their respective fandoms? Have Mary Sue comparisons been drawn in those instances?
Coming in a bit late on this, but I see that no one else has addressed this. Trek was my first fandom, and I've tried to keep at least a finger in the water there. Maybe I'm just fuzzy brained right now, but I can't place any Trek novels that he was involved with. Maybe I never got or read them, or maybe I've just forgotten. The only ones I remember are his nonfiction bios about the show, and his Tekwar series (which were actually ghost written by an SF author named Ron Goulart, from Shatner's plot outlines).
However, an instance which DOES apply to your question involves an actor named Paul Darrow, who starred in a British Science Fiction Series called Blake's 7. He wrote a novel (Avon: A Terrible Aspect), based on his character, Kerr Avon. The novel was a prequel, set just prior to the opening events of the tv series. As with LP's book, opinion varied widely, but the majority of fans were not happy with the book. Dredging up my memories from close to 15 years ago, I remember the major exception being the character being "off" from the series, and the style being more hard boiled detective novel invulnerable protagonist cliche than the 1984 type atmosphere of the original series. I DO have strong memories of a friend in the publishing industry being so annoyed with the writing style that she took a blue pencil to it, for sheer theraputic purposes.
Then again, referencing the above about Shatner and his ghost writer: at least Darrow and (to bring this back to topic) Parker did their own writing.
One other example that just popped into my mind as I was about to post this is a Forever Knight novel co written by Geraint Wynn Davis. I remember that one being true to the series and the character and well received by the fandom.