I've never read any of the Stargate franchise novels before Karen Miller's “Do No Harm”. It was an excellent introduction to the novels that was completely impossible to put down until I had finished it!
The novel gives a fascinating glimpse into Jack O'Neal's past, and his relationship with others that knew him before he joined the SGC. Even more so, Janet is portrayed amazingly well, and we begin to understand what drives her, both in the work she does at Stargate Command and her relationships with the members of SG-1.
All of the characters are believable, and true to their personalities as portrayed in the TV series. I would definitely recommend the book!