This book has a lot of my personal favourite topics - i.e. mystery, history, fantasy, travel, Bulgarian lore, etc. I've kept it on my TBR list for a long time, because I was both itching to read it and dreading being disappointed, as is often the case with books that should theoretically hit your sweet spot.
End result: I'm on the fence. 

There were too many POVs, for one, and the characters weren't fleshed out very well. I would have lost track of who was supposed to be speaking, if the narrators weren't doing the proper voices and accents. 
Another thing that didn't jive with me is a good half of this was told through letters. Don't get me wrong, I like a good epistolary novel, where I can get a taste of the characters through their prose. But this wasn't it. 
And it dragged something awful in the middle. I'd have preferred a more streamlined narrative, instead of all the tedious description.