As far as the film goes, it's great. The story is captivating, and the writing is excellent. And as much as it pains me to say, Leonardo di Caprio's acting is top notch! I'm not going to talk about the story, I'm going to review the HD experience you're getting:
Visual: Blood Diamond looks really, really good in HD. The landscape shots and action sequences are so crystal clear it makes you think you're a part of the action. I didn't expect the film to look as good as it does, and I recommend it highly. There is no visible grain, pictures are clear, sharp and the colours are well saturated. Definitely better than expected!
Audio: The uncompressed 5.1 surround is truly breathtaking! Sound is clear, deep and well equalised to deliver a near-cinema experience. There's no distortion, and the sound is well levelled throughout (so no theatrical sound needing you to turn it up and down constantly!)
Overall, I'm very happy with the way this turned out. It's a beautiful film that's written very well and looks incredible on blu-ray.