I was so confident I had read this book years ago, but nothing from it seemed at all familiar, so, for whatever reason, I must have stopped at the second book...
I will say I was disappointed by this one. For one thing, I hated how there was so much confusion over Daniel calling Katherine "Katie". I don't know why the butler wouldn't have any concept of the possibility that someone from Katherine's old life might try to contact her. Why would he assume Daniel was referring to the impostor? It was too obviously just a way for Daniel to come frustratingly close to Katherine without a reunion actually taking place.
I also was very unsatisfied with the ending. Katherine is perfectly happy living in the mansion and using her wealth to help others until she suddenly turns around and decides she's not happy living that way, so she ditches the mansion and becomes Mennonite instead. It was so abrupt. And I felt like the book was claiming that it's wrong to be rich or to enjoy nice things. I would have bought her happy medium if she had found herself becoming obsessed with her riches, but that didn't ever seem to be a concern.
I thought there would be more of a love triangle, but it was clear that Justin was never a contender. There wasn't really much substance to their relationship at all. It makes sense to me, though. As if dating Justin was just a part of testing out this new life she has. This isn't really a complaint. I don't mind love triangles, but they are a bit over-used these days.
Combining the last two points, maybe it would have made more sense if Katherine's faith in God wavered and dating Justin was part of that, considering he was so apathetic toward religion. That would have achieved the same end, and been more believable and satisfying, I think.