This was quite the thrill ride. I love most anything Jack the Ripper and this dual POV was interesting. The story kept a good pace, a little sluggish at times, but nothing too slow. Jack's journal kept the mystery of who he was, but showed an intelligent man on a mission. At one point I made a guess of who he was and at the end I wasn't wrong, but there was a nice twist that threw me off and kept me wondering. 
 My only real complaints were both Jeb and Jack got wordy. They both went off on these tangents of lists that went on for 5 or more things to describe one thing like Whitechapel and it was like "Get on with the story. I get your point." My other complaint was the bit with the rats at the end. It wasn't realistic as rats are cautious and shy creatures. They wouldn't just attack like that--even if hungry. (view spoiler)[It would have been more realistic if they had shot the Jack and have him die and the rats creep out and start nibbling at the corpse than the rats piling on him while he's alive but injured. Made it gruesome, but a bit far fetched.. (hide spoiler)] 
 Overall, a great story. It didn't deviate too much from what really happened, trying to keep the details accurate with few deviances.