As far as the film goes, Letters from Iwo Jima is a classic. It's a truly heart-wrenching story, and a testament to both the Japanese army's struggle to protect their homeland and Clint Eastwoods' directing ability. Enough about the story, let's talk about the High Definition aspects.
Visual: Letters from Iwo Jima is a film that's done entirely in a semi-desaturated way. Draining colour in the same way the film drains hope from the Japanese armys' situation. All in all, the effect is marvelous and I think it adds so much atmosphere to the film. There's virtually zero grain, blacks are deep and detail is sharp throughout. Visually, this film deserves a 5/5; the transfer is so clear and sharp that the picture is always breathtaking.
Audio: Dolby TrueHD really does the job here. Explosions are deep and resounding, and speech is clear and perfectly audible. The films' audio is well-levelled throughout so whether you're in the middle of an action sequence, or a quiet speech, there's no need to keep changing the volume around.
Extras: Sadly no directors commentary, but you do get the standard behind-the-scenes footage, on-the-set photos and so on..There's also a cool featurette where the cast talk about their characters, which is an interesting addition.
Overall, Letters from Iwo Jima is a great example of a blu-ray disc. Pristine quality matched with a great story. I would have liked to see more extras, but all in all this is definitely a film to add to the collection, war-film fan or not. Hope this helps.