It's the equivalent of Super Mario Bros. 3, but for the original Game Boy.
Each of the 6 zones has its own environmental motif. For instance, "Turtle Zone" has an underwater theme while "Pumpkin Zone" contains references to Halloween. Additionally, for an original Game Boy game, the stages are highly-varied and fun to play. In one stage, Mario is jumping across floating leaves, while in another, Mario is swimming through a sunken ship!
The game has two modes: "Normal mode," which is automatically chosen when a file is picked, and "Easy mode," which is enabled by pressing the select button while on the file selection screen. This option can help attract beginners to this game, despite the fact that it does not alter game play all that much. In fact, the only major criticism I have for this game is the fact that it is too easy, even while playing the normal mode. Yet, this still does not detract much from the overall experience.
All in all, Super Mario Land 2 completely eclipses its prequel in every respect. It is a game that should not be missed by fans of the genre, and is fun to play, even today!