My dad once said to me, "You give a lot of books three stars." I do.
Spoilers under the cut.
Dan Brown knows how to make readers turn pages, but I thought Inferno was his weakest book that I've finished (I only made it 100 pages through The Lost Symbol but I enjoyed his first two Robert Langdon books).
I hated the part of the book that took place in Philippines. It was really reminiscent of the scenes from The Avengers that are set in India. It's just a backdrop for the white character's development. Brown also uses the slur g***y to describe a woman in Venice. Doesn't even bother to give her a name. I also hated how Vayentha's death is never really dealt with.
The prose is pretty purple at times (that might have been the case in Brown's other books and I just didn't notice/it didn't bother me). And there are some pretty obvious bits that take forever to be revealed. The most noticeable one being the horses in Venice.
Sinskey's infertility is mentioned way too much. At first it felt like a weird sexist thing (woman is obsessed with lack of ability to be a mother) but then later it sort of ties into one of the twists (not really, but it gave the twist away for me).
All in all, not Dan Brown's best. I think after the disaster that was The Lost Symbol (so boring I couldn't even get into it) and the letdown that was Inferno I'm done with Dan Brown.
ETA: Dan Brown writes so slowly, I obviously forgot all my annoyances with this book. I will probably continue to read Robert Langdon books as long as he publishes them because while they are often annoying, I do enjoy them on some level.