After a very weak season, Torchwood finally finds footing with a fantastic work of pathos and humanity. The story presents life in a very refreshing way, random and hopeless yet wonderful and inspiring. The plot works well for the most part, but is mostly just a backdrop for the character of Eugene to come to terms with mortality. The non-linear pathway to tell the story greatly assists, however, and presents an otherwise vanilla story with grace. Sidelining many of the main Torchwood characters also greatly helps, bringing out the far more interesting Eugene and the people he interacts with. Some parts make little logical sense (particularly a certain moment at the end), but when presented so effectively, it's difficult to care.
Overall, it's a very rewarding episode to view, and is a lovely subdued moment amidst the chaotic loudness most of Torchwood presents. In my opinion, it is without a doubt the highlight of the first two series, and one of my favorite pieces of television in general.