I saw the film with my sister and we both liked it. I do think that the film suffered from too much Hollywood action...in other words, WAY too much time on the Mr. Jekyll monster smashing things. I imagine that was done to appeal to the adolescent crowd.
Those who are unfamiliar with 19th century literature wouldn't have understood Dorian Grey's fear of his painting, nor the portraits of previous "Leagues" on the wall of the headquarters, one of which contained the portrait of the Scarecrow of Romney Marsh. I am also certain they were confused about the Carnival in Venice, the Ishmael reference (which at an afternoon matinee most people in our audience laughed at, since most were over 45) and the references to Alan Quartermain's adventures.
The acting was excellent. Sets and special effects were fabulous.
I think I would grade it as a B. See it at a matinee or with discount tickets. It is better than much of the schlock out this summer, however.