There have been some rumblings about the 'Half Blood Prince's transfer. The rumors have consisted of a myriad of problems that may exist with Warner Brothers' product. I hope to address those issues here.
It was mentioned in our forum, by forum member Hogarth, that the disc he bought was defective. He mentioned watching it and having lighter bands appear at a certain interval in the film. Following the time stamp given I watched the scene (timestamp 1:12) and couldn't see anything wrong with the transfer. I didn't see any lighter horizontal bands appear at that time or any other time during the film. Hopefully this problem, if it is a defect in some of the Blu-rays, is localized to a certain group of discs and is easily replaceable.
There has also been talk, around the web, about groups of artifacts muddying up the screen in certain areas. I hope to straighten this out right now. Take for example the timestamp of 47:47. It has been said that Lavender's face is completely confounded by artifacts. Indeed if you travel to that point in the movie, you'll find that her face is quite hard to see, but it is not because of artifacts like blocking. Instead I believe that people may be confusing the heavy layer of grain in this film, for digital artifacts. The grain is very heavy here, but it still isn't as heavy and nauseating as it was in 'Burn Notice: Season 2.' The grain ends up creating an artifact-like mess, because the movie is so outrageously dark by design.
When I previewed 'Half Blood Prince' in the theaters I did notice a very processed and stylized look to it. All of the colors are muted. Soft mustard yellows, dingy greens, faded blues, and soft earth tones take over the film. If it weren't for the engulfing darkness that constantly surrounds every scene, I'd think I was watching a Wes Anderson film.
Because of the heavy grain, the film does lack some fine detail, especially in the characters' faces. Crushing shadows persist throughout the movie. This is a directorial choice, but nonetheless, it does hamper the details at times. The overly stylized look also plays its part in making fine detail unnoticeable.
Overall the dark, grainy, and muted video presentation is representative of what the director envisioned and how it appeared during its theatrical run. Because of the crushing shadows and lack of fine detail, this wouldn't really be a disc you'd show off to friends as demo material, but it is a disc that is free from malicious artifacts, as far as I can tell.