To be honest, I haven't finished reading the last two volumes for GH yet. ^^; From what I've read, the plot is pretty much the same although with a lot more detail and stronger writing compared to the original novels. The one change I've noticed is the removal of certain minor scenes between Naru and Mai; the ones that hinted at NaruxMai. (One scene in book 2, and part of another in book 4. I need to double check book 5 and see how things went in there if things are the same or if anything changed.)