When I hear this piece I am reminded of Marvin, the manically depressed robot in Hitchiker's Guide to the Galaxy. A sad and depressing piece of music intended to convey the change in mood from the light, happy children's story of the first three books to the 'end of the world' scenario that becomes the main focus of the rest of the series.
Included is a short theme devoted to the Weasley twins; a half-hearted attempt at a celtic reel performed by screechy violins and whatever else they were able to drag out from under the sofa.
In short, this score carries all the spark and flavor of a soda that's sat opened on the counter for over a week.