Books are usually better than their screenings. This is somehow logical, because the adaptation changes the source material to accommodate it to another and completely different medium, whose explicitness could never be compared with the infinite possibilities of crossing the imagination of the author with the imagination of the reader. But it seems that even when things are going in the opposite direction, the books still win.
"Neverwhere" is a British mini-series that Neil Gaiman wrote directly for TV, and then subsequently turned its scenario into a novel, which changed from release to release until it became one of my favorite books, which series on which it is based exceeds in every respect. Although it's BBC, the series is low-budget or at least looks cheap. Also, there are only six half-hour episodes, and the potential here is quite enough for at least ten times more, which would allow a more detailed story and better character development. But that does not mean it's bad. On the contrary, I liked it, because it very convincingly fits quite original fantasy world into our reality. The main problem is that the actors can not play, the director cannot direct, and studio and filming locations cannot look as good as I can imagine when I read a book.
Any attempt to give you a brief idea about its plot finished as a spoiler, so I'm giving up on that intention. The mere fact that it's written by Neil Gaiman should be reason enough for you to take a look.
9/10 for author's imagination
5/10 for the technical realization