I can't talk about the book, but compared to the first one it seems like this got a little lost: even though the characters got the central attention, it seems like they lost the development they had in the other one.
In the second installment, our girl is even cooler than before. Since I do not read the book, so most of the plot was cleverly yarn to give continuous surprises in finding whodunnit result. Supported by committed casts, no Hollywood effect is in need to make this film sparks the big fire.
Indeed, in contrasting this film with its predecessor, the change in style is apparent in the first few minutes of the film. Namely, the lighting is not as dark and the cinematography is not as crisp, lush and thoughtfully presented. [imho]
Yet, overall, I must say I think the film is quite a good watch and furthermore, I find it quite faithful to the narrative initially presented in the series' first installment.
This installment didn't command my attention like the first one did. Still great performances and a fine mystery - and the wringer they put this girl through as the conclusion nears borders on torture porn. (That was a compliment.)