I saw the movie of The Woman In Black back when it came out and was not terribly impressed by it but liked the story enough that I decided to go see the play while I was in London.
The play is a lot better than the movie, more interesting a creepier, and I considered going to see it a second time while I was there. (Didn't actually make it, but I did think about it.)
That being said, creepy things are a lot less creepy when a theaterful of teenage girls screams at every single tiny little thing and makes the next several lines of dialogue impossible to hear.
There's also a thing that happens in the play that I think is supposed to be a surprise but is pretty obvious from the moment it's set up much earlier in the show, and it makes the whole thing very sad.
I still highly recommend going to see it if you happen to be in London. Just try to go to a performance that isn't full of teenage girls.
End of line.