This was an entertaining read for a lazy afternoon, not more and not less. That's quite a shame because it could actually have been more if Anna's character had been given more depth and some flaws. As it is, she has deductive talents that equal those of Holmes but neither his drug-habit nor his tendency to constantly offend people. Additionally she's a bacteriologist but the master in this field. There is also That Horrible And Tragic Event In Her Past (TM) (that is just there to add some shock value without going much in the consequences it should actually have for Anna).
My Mary Sue-senses are tingling. Anna does no wrong, at least in the first half of the book. In the second half she does make decisions that can certainly be described as morally questionable but to be fair to her that's mostly in situations where she has only the choice between a bad and a worse decision. She also beats herself up about it afterwards but considering she had no real choice it's hard to mark this as mistake or character flaw. Anna is just the pure innocent angel who has to kill an already dying person to save her own life and potentially that of dozens or even hundreds of others.
We also hardly learn anything about her motivations. Did she just stand up one day and say "I'm going to study medicine but because women aren't allowed to do that I will dress up as a man."? Because that's what it looks like. There's a mention of her mother being a very intelligent woman but that's about it. I don't need five chapters of infodump-backstory but that was a bit like joining somebody who is already half-finished telling a story and nobody even gives you a short overview of what you missed.
I did like that it was made clear that dressing up as a man all the time is not the same as just going to a fancy-dress party but actually takes a toll on one's mental well-being. However it gets mostly alluded to and is more told than shown.
More details there, and generally in the last third of the book would have made quite a difference. Towards the end the plot just rushes along and before you quite realized that this is the climax of the book it's already over.
All even more disappointing because the writing-style was really good and with a better main character the book could have been as well.