A little bit of everything
Vice: Project Doom was released at the end of the NES's life-cycle so it didn't get a lot of hype or notice (though I do recall that Nintendo Power covered it briefly). I was recently reminded of it through a Podcast that was saying how great it was. Having never played it when it was new, I decided to find it and give it a chance.
The game takes aspects of different classics and brings them together in one package. The story presentation feels very "Golgo 13" (many would compare it to "Ninja Gaiden", but I think Golgo is closer, honestly), with a definite noir feel and lots of detailed close ups of the characters faces. The game play has overhead car levels like Spy Hunter, side-scrolling action levels like Mega Man or Ninja Gaiden, and first-person shooter levels like Hogan's Alley or Gotcha.
The difficulty ranges from really easy to insane, with the car and first-person shooter levels being a breeze while the side-scolling levels are as unforgiving as games like Mega Man or Contra, where you'll find yourself dieing a lot of cheap deaths until you memorize where the mobs will spawn and how they will act. The bosses found at the end of each level also range in difficulty -- some can be killed without your hero having to move, some put up a decent fight, and the final boss is nearly impossible.
Hart has three weapons -- a whip, a gun, and grenades, though you'll only be using the whip for about 95% of the game. The other two have limited ammo (with more dropped randomly by enemies) and are only useful in certain situations (eg. the first-person shooter levels will obviously use the gun). Hart also has a health bar that seems on par with similar games such as Mega Man and you'll probably find yourself dying more to getting knocked into inconviently placed pits than from reaching 0 damage (except against bosses).
You have three lives until hitting Game Over, at which point you're sent back to the beginning of the level. Unless you play with a game genie or an emulator, you'll be dying a lot and restarting levels often -- especially towards the end of the game. This level of frustration might have been on par with other games at the time, but nowadays it's just needless tedium, taking away from the enjoyability of the game.
The game stretches across 11 levels and takes about 2 hours to beat start to finish with a fair number of continues used. It's certainly one of the better looking games on the NES and the score fits it nicely (though one or two tracks are really sort and repetitive). The dialogue leaves a little something to be desired, but it's the NES so what can you expect? If anything, it was refreshing to see a story geared towards a more adult audience, mentioning things like "forensics".
Overall it's a decent game and certainly worth checking out if you're into old school games like Ninja Gaiden, Megaman, or Spy Hunter and don't mind trail and error gameplay and a lot of cheap deaths.