Possibly the best port of Super Mario Bros. I have ever played.
Aside from a few animation changes and smaller screen, the original Super Mario Bros. has remained fully intact. The graphics,music, sounds, levels, and enemies are exactly the same, which is by no means a bad thing. Some of the changes include added animations to water and lava and a couple of characters, a map screen (pressing select on the map screen lets you switch to Luigi), and of course the view of which you are able to see the level. Since you are playing on a smaller screen it zooms a bit more closer. To could present a problem in certain parts of the level as you couldn't tell what's below or above you. To solve this the game allows you to pan the screen up and down to get a better view in whatever direction you plan to go. It can still be a bit problematic, but not to the point of frustration.
Aside from the original game there are some cool added bonuses. The game has two other difficulties to test your skill. The first difficulty is what I like to call the star difficulty, because by scrolling through the levels you come across a new set of levels with a star replacing the dash in-between the two numbers. In these levels there are more hazards and all the Goombas are replaced with buzzy beetles which you cannot destroy with fire balls and they can be more challenging to deal with in walled sections. Finally the last difficulty is actually the original 8-Bit port of Super Mario Bros. 2: The Lost Levels, originally released in Japan and ported to the Super Nintendo in Super Mario All Stars. Included along with the different difficulties include a versus mode, coin challenges, and Boo races. All of which are very nice touches in the end.
To sum things up:
PROS:
-Original 8-bit graphics
-Levels, enemies, music, and power ups are kept in tact
-Added challenges for replay value
-The original Lost Levels
CONS:
-Zoomed in screen can be a problem sometimes
With all of this great content combined, this is definitely the best port of Super Mario Bros. you could ever play. This is basically a must own for your Gameboy. Just like the original NES cartridge, this is guaranteed to last you for a long time. For those looking for your 8-bit Mario fix on the go, look no further than this game.