We just blew through the eight episodes that comprise this series (apparently it's been renewed for a second) over the weekend. Wonderfully written, amazingly acted, tightly paced—this was just an excellent watch all the way around. It has genre actors in it—David Tennant (who was allowed to run gloriously free with his Scottish accent); Arthur Darvill (Rory is a vicar!); and David Bradley (he'll always be Filch first for me, but most know him now as Lord Frey).
Not only is it a well-written murder mystery, it's also an excellent (and often painful) character study of a small town—and what living in such a place is like, and can do to people.
If you read a lot of police procedurals/murder mysteries/serial killer books or novels (like I do), there's a chance you may figure out the culprit before the end (like I did). This in no way lessens the impact of the reveal and its repercussions.
Highly recommend this, and can't wait to see what the second season will be like.