I give Pam Conrad high ratings for masterful storytelling. Grandma's character is well developed (though other characters less so) and the story certainly engages the emotions and interest. .
My Daniel deals with a lot of heavy issues for its intended 9-12 audience, however. Disappointment, death. dying, grief – even a secret and unpunished murder – fill the pages. The bittersweet comfort of memories and family ties offers a positive note, though the thread of secrecy between parents and children leaves me cold. There is little in the way of noble character inspiration and quite a few poor choices not dealt with. The story is not especially historically accurate nor highly educational, and only tidbits can be gleaned related to paleontology, which would likely be appealing to some young wanna-be naturalists.
In the final analysis, I am left feeling neutral about My Daniel , leaning towards negative for the stated 9-12 age range. If you decide to have your children read it, I'd certainly suggest parental involvement and discussion.