The most historically accurate piece of fiction about the lives of the Romanov sisters I've had the pleasure of reading.
The writing is beautiful and the different voices have a way of being similar enough that you honestly believe the speakers are all close siblings but different enough not to get redundant.
I also give this a big thumbs up for following the girls' story all the way to the end where they meet their tragic deaths (this shouldn't be a spoiler, considering it's history and most people know this happened). Most books of this sort seem only to go up to their time in early imprisonment. Except for The Tsarina's Daughter which I did not care much for, and thought wildly improbable.
I DID like House of Special Purpose, which also follows them to the bitter end, but that took a LOT of obvious liberties.
One cool thing about this book (The Lost Crown) is that its one of the few fictional books you can bring up in the presence of a 'Romanov purist' (aka a particular brand of history buffs who hate most fictional portrayals of the Romanovs, and get smoke coming out both their ears if you mention Don Bluth's Anastasia) without causing them to foam at the mouth. This book has won even most of them over for its beauty and Historial accuracy. Which really should speak for itself on how GOOD a job Miller did here.
If asked if this or Meyer's slightly more recent Anastasia And Her Sisters (along the same plotline as this one) is the superior piece of Romanov sisters fiction, I would have to admit that's not an easy question to answer. Both books have VERY good, historically accurate, portrayals of Anastasia and Olga Romanov.
Here are some points to consider if you're planning on reading only one of these similar books and are debating which to choose.
1) The Lost Crown, strictly as a novel, is better executed. You get a look into all four of Tsar Nicholas' daughters' heads, not just one or two. And through each of them a more solid idea of the others around them. From Olga and Anastasia's pov chapters, I felt very connected to their little brother. From Olga's alone, we get a better view of their father. From Tatiana, we understand their mother Alexandra and her struggles. From Maria, you get more sympathy for persons outside the strict family unit, such as the guards.
It also just has a better flow with natural dialogue. At no point did I feel Sarah Miller struggled between writing this as almost a text book and recalling it's really a novel. She knew what she was doing and she did it well.
2) Despite the brutal realness, The Lost Crown leans a smidge more towards sugary sentimental views on the royal family than Meyer's book. You never quite get the feeling Olga is more depressed (or even angry) than her sisters in Lost Crown, which it seems likely she was in real life. Even the gun she conceals on her person until she's forced to give it up is not shown in a sinister or ominous manner; its just for protection. If you lean more to the view that all four girls were largely uninformed of the danger of their situation beyond a few inklings, Miller's work will keep you with that assumption. Meyer's seemed to have darker implications, with Olga growing bitter and Maria almost blissfully oblivious in contrast, Anastasia caught someplace in the middle.
3) Timing/romances. There isn't really any romance in The Lost Crown. This could be because it begins later in time than Meyer's, so there was no place to include Olga/Pavel. But any other possible crushes, such as with soldiers in the hospitals, or their own male cousins, aren't touched on either in Lost Crown. The book doesn't suffer for this in the least, as it wouldn't have added anything important, but it is a major difference between the two works. Meyer's book not only touches on Olga's ill fated romance, it strongly implies Anastasia may have been in love with Dr. Botkin's son.
So it comes down to preferences. If you want more showing and sentimental views, Lost Crown will please you most. If you want more telling, with a cynical edge, try Meyer's book.
Personally I love both, but I think this book, Lost Crown nails the story of the tight knit family better, while the other one is broader and more clinical.