Metal Slug the arcade game is a good game in my opinion. But lets go deeper into why this is a good game.
Basic Info
Metal Slug is a Plat former and a shooter game. Developed by Nazca Corporation, and released in 1996, it was reviewed fairly well by the public for having thrilling game play and a good sense of humor.
Control
Lets go over the controls. Its simple. Move left and right with the joystick and shoot with the A jump with B and throw a grenade with C. Its very easy to master and anyone can just jump in.
Sound
The sound is great. The game has music that just pumps you up to kick so major behinds. The enemies  screams sound real and so dos the gun. But sometimes the screams do get loud and annoying.
Graphics
The graphics look like cartoons but nothing too bad. And sometimes the graphics just pump me up.
Story
The story is that The evil General Morden and his rebel army has launched a coup d'état on the world's governments, and all attempts by the armies of the various countries to curtail his growing power fail. His most recent attack has given him access to a new form of all-terrain combat tank dubbed "Metal Slug". In a last effort to stop Morden, Cpt. Marco Rossi and Lt. Tarma Roving of the Peregrine Falcon Strike Force are sent to locate and eliminate his powerbase, as well as reclaim or destroy any Metal Slugs they can find so as to keep the technology out of Morden's hands. But nobody plays this game for the story. It is a kinda realistic story though.
Extra Content
The game doesn't give you any extra content other than the main game, but the game is very fun to play so extra content is really necessary.
Difficulty
The difficulty is handled very well, getting harder the farther you go, but expect to die a lot latter in the game or on your first time through because this game has Contra logic, aka you die in 1 hit, if your not in a tank. Oh yea, the tanks are a powerful machine's that have missiles instead of grenade and a machine gun instead of a regular gun and they take multiply hits to take down. But you can only get them once per stage.
Length
The games length is short, seeing as there's only 6 levels which can be long at times, but there's only 6 stages. But the game should be short seeing as its a arcade game (there short so people don't spend all day at the arcade.) and again the game can be hard sometimes. The game can be long in 1 player, but in 2 player it can be done in 50 minutes.
Overall
overall, i think Metal Slug the arcade version is a great game, with a blood pumping sound track, great game play, controls, and a good story, I give Metal Slug a great score of 9.5.
This is the slender Luigi, sighing out.

I must really say, that is a pretty good review. You have pretty much summed up the whole review and it is a very interesting review. What I can suggest to make your review even better is to put some spacing and categorize it so it can be easier to read. From what I have seen, most users seems to laze out whenever it comes to reading one big paragraph instead of several small ones. 

Here is an example:

Intro:

Intro stuff, talk about the background of the game... etc.

Graphics: 8

Talk about graphics stuff... etc.

Sound: 9

This game has good sounds... etc.

And so on with the other categories. This is not mandatory but it is something to start off with to help you make even better reviews!

Anyways, awesome job man!  

mohammedroxx3 : Thanks for the info. This was my first review ever. So any info i can get will be helpful.