There are some things I really enjoyed about this book, and some things that didn't quite work for me. However, overall it does exactly what a good splat should: It made me want to run a game based on it, and feel more prepared to do so.
I really enjoyed the dives into the themes of Victorian age stories and how to use Lost to highlight those. The explorations of what the world was like, how it was changing, and how that affected the core setting of Lost were also well done. For me, this is the meat of the book and the merit of the rating I'm giving it.
As a quibble, I don't think it was necessary to say the kiths and contracts presented were Victorian specific - why would the Gentry respond to worldly events that quickly and specifically?
Also, I would have enjoyed more resources for depicting Victoria's London with a bit more historical fidelity, as opposed to just a steamy set dressing. However, it gives a start (and, for those of us who are into such things, there are many resources available). Indeed, most of my 'complaints' involve wishing there was more - this could have easily been a full book, and I would have happily paid for it. However, I appreciate their decision to make it slimmer source of inspiration, and think that it earns its page count well.
Most games set in Victorian times seek to bring the mortal class system into their game world: here, showing the mirror of the mortal class system as a caste system for the Lost requires a bit of a stretch, and I'm not sure I'm buying it completely. While it does provide some interesting avenues for conflict and concerns of identity and place - it takes a few too many handwaves to really be comfortable for me. A born Peer of the Realm who is abducted and made into a Wizened Soldier or Antiquarian suddenly at the bottom of the class system, while a cockney flower girl turned Fairest rules? Perhaps if I saw how this worked out with more full examples of ruling courts, I might buy into it - but, as is, I'll likely drop it. Fortunately, the book retains its value and utility. (This is most of what keeps me from giving it 5/5, though).
The sample adventures seemed a rollicking good time, suitable for different play groups, and the characters seem flexible enough to bring to a new table and have people find somebody they can enjoy playing. The art was thematic and well executed. Overall, I enjoyed it and would recommend it to anybody who enjoys Lost. For people who aren't into Lost, but love the era and setting (and might be looking for a game to run in it)... I would also say give it a try.
[4 of 5 Stars!]