Most interesting aspect: the movie was filmed illegally in China by Stanley Kwan. It was adapted from the popular erotic novel, "Beijing Story," which first surfaced on the internet. The movie isn't any more erotic than a typical 'R' movie. There is a brief bit of relaxed full frontal male nudity towards the beginning (which means there's no point in putting it to the MPAA), but the camera never shows anything too sexual, so those expecting erotica or porn will be disappointed.
There's an intentionally reserved quality to the acting that conveys the difficulty the two men have with their relationship. The older controls the money -- which the younger, Lan Yu, needs -- but the younger controls the depth of the relationship -- which the older, Chen Handong, sorely desires. Mr. Chen is shown both simply wanting Yu, and wanting to control Yu (to ensure Yu won't leave). Along with this, the film finds ways to express both Yu's powerlessness, and protective aloofness. Yu's only control is to remain distanced so that Chen must take actions that an uninterested man would not, and thereby reveal he does have feelings for Yu. When Yu dares attempt a show of affection, circumstances are against Yu, and he ends up retreating.
The subtlety of acting combined with good direction and camera work help the film overcome a weak script. Individually, each line is fine (and often quite witty), but the overall plot is contrived and the story feels rushed. For a romance, it isn't any worse than a typical script -- as they all tend to be weak -- but it doesn't excel. Also, the typical Romance genre film uses Love as force to sweep the audience away, but in "Lan Yu" the caution (from fear of being caught, fear of getting hurt, etc.) and the cultural manner of reserve makes the film less able to distract viewers with emotional charges.
Most the sets are rather dark (suggesting that they couldn't get big brights without attracting attention), so the film doesn't have much light in it. This works to create a mood that jibes well with the story. The cinematography is excellent and has some very nice choices. For example, there's a scene -- without dialog -- where Chen is worried about Yu, and when they meet, the camera shows only Yu's back and the urgent grip of Chen's encircling hands. There's also a nice use of a mirror to show distancing as the two leads conversed).
The film does some of its best work without any dialog, and in one case without sound. The latter is near the end, and the removal of sound heightens the drama of the moment. The voice-overs don't work well. They reinforce the theme, but feel clunky at it. It is impressive that the director was able to visually describe so much, but there is a definite sense that compression from book to script length disrupted the story's flow.
All in all, the movie is fine for folks needing more movies that are serious, non-porn stories of gay men.