The original Rambo is more than just a guilty pleasure for action enthusiasts. While the latter two in the trilogy are arguably just popcorn flicks in terms of their overall impact on the industry as a whole, the first movie, appropriately titled First Blood, was a legitimately good film.
It dealt with the very real troubles of soldiers returning from war to adjust to normal life, in this case, specifically targeting the Vietnam War. Although Rambo is often regarded as a cold-blooded killer, he only actually kills one person in First Blood -- by accident. Eventually, the series would get progressively more ridiculous and further removed from the original's message, culminating in a mess of an experience called Rambo: The Video Game.