Instruct: Classify a given Amazon review as either positive or negative.
Query: Deep disappointment

I am a fan of the National Geographic series, but the poor quality of this relatively new issue was a deep disappointment. Rather than tracing the flaws in design, production, or emergency procedures through the evolution of the submarine (as I had expected), the documentary spent a huge amount of footage on filler, including a lengthy bit of fluff about the fun-loving antics of a current submarine crew. The facts that led to the demise or near-demise of each submarine were glossed over, while the camera dwelt at great length on the anguish of a few of the survivors. The incidents were presented nearly free of scientific content or historic context.