One of the best NES games ever, and the best of the NES Mega Man games.
The graphics were clean and pretty amazing at the time, with little slowdown. Mega Man still had his same old animation for running, gunning, etc. but with a new slide thrown in for good measure. Sound-wise, the game's music shines as being the best Capcom's put out for the NES. It's amazing how much they could coax out of the NES for the sound. Gameplay is the typical Mega Man game: choose a boss, fight it out with the boss, get the boss' weapon, use the boss' weapon on another boss. Lather, rinse, and repeat. Granted, Capcom made a nice swerve after beating the initial eight robot masters (why didn't they do something like this in later games?). The game's challenge rating falls somewhere between moderate and easy, though one particular boss (Rockman aka Yellow Devil) is a pain if you don't know what weapon to use.
Probably the fact that this was the last really good Mega Man game, and that those that followed were cookie cutter made (you knew who you were up against all the time, in reality), with some truly strange choices for robot masters. As for Mega Man 3, the disappearing platforms that Capcom loved to throw in throughout the Mega Man series rear their ugly heads again, and can become annoying if you don't know the pattern. Plus, one sequence does require the use of the Rush Jet for an extended period, and if you mess up and have to restart with a less than full energy meter, you're in for a world of hurt.
The Bottom Line
Simply put, the game is one of the best the NES offered, and truly was Nintendo's 'other' NES mascot. While Mario might be the king of action/adventure for the NES, Mega Man was right up there as well. Grab this game and don't let go.