I didn't like SNOW MOUNTAIN much either. This book, SUMMER DAY..., is how I like my Romanovs...
I haven't read this one, although I would like to. I do, however, love The Snow Mountain. I loved the fact that it was non-sentimental, that it portrayed the Romanovs as real people and real young women with their own issues and struggles growing up in a difficult position. It may or may not be truer to real life than "Summer Day is Done", but I enjoyed the characters and thought this was how it could have been. A more sentimental version may be an easier read, but I like a bit of grittiness in my historical novels, especially ones dealing with tragic and interesting times.
I also liked the subplots, which contrasted to the lives of the Romanovs- in particular the Mara Trenova one- a young girl who joins the revolutionaries only to be disillusioned and come to a tragic end. A fully realized and brilliant character, I thought- historical fiction at its best.
This is just my opinion, of course. Everyone has their own tastes!