The notion of throwing together current Dr. Who and current BBC Sherlock is obviously appealing. However, I found this story works only on a basic level. The main characters and relative back stories seem a tad one dimensional, with some inaccuracies of detail (e.g. Amy and Rory never cared for an infant River Song, as they are apparently doing while this story occurs. She was abducted as a newborn and next met her mother as a teen--unless this is meant to place us in a parallel reality?)
I am more of a canon-verse Sherlock fan so maybe I am not the best audience for this story. But at the same time I am familiar with both modern shows being mixed here... and I think so much more could have been done with combining them. But I did enjoy the charming little Mycroft/other subplot.