It is nice to see Daniel Radcliff in a post Harry Potter scenario, and he confirms his acting chops quite well in this thriller. The thing I liked the most about this was the complete lack of 21rst century gore that still managed to be extremely frightening. There are cgi and special effects but they are kept to a minimum and used very sparingly to maximum effect. Note, this movie does not come across as a budget production that is trying to save money by not showing things, but rather, an understanding per the old school of filmography that less is more and what you imagine to scare you is infinitely worse than the hockey masked psycho with a chainsaw cutting people up in three d-smell o vision so visceral that you might feel like you are there. Technology may progress to a point where you can literally FEEL everything that the victims of a horror movie experience, but movies like "the Woman in Black" will still be great works of art because of what they DON'T show you, long after the most current techno thriller numbs your senses and desensitizes you even more to the violence.
The plot is quite good and slowly dolls out its secrets in a manner sufficient to keep the audience engaged with enough dialog to keep the intelligent interested and enough action or suspense to keep the adrenaline junkie interested as well. The opening sequence is enough to attract your interest right away, and also sets the stakes for what is to come. Normally, I wouldn't hesitate to tell you about the first thirty seconds of the movie (spoilers are for endings and at best middles) but in this case in case you haven't seen the trailer I want to keep it a surprise. Speaking of endings, the twist at the end is... surprising even if the events that lead up to it are not. The supporting cast is also equally fantastic.
The thing I really liked about the whole thing was the consistency of the world and/or plot. They stayed within the regular tropes of the supernatural whilst at the same time adding some of their own unique elements. The characters you don't always care about or think about (specifically, our supernatural friends) are actually consistent in their behavior and do what you might expect them to do given the rules that the movie sets up (as compared to, Demon X who merely shows up and kills people because it might make a scary moment in the movie.)
In short, I highly recommend this movie.