It is the first level to have two huge waves of zombies. The player may not be used to having a big wave of zombies until the end of the level.
Levels with two flags tend to be longer than levels with one flag, however this also means more time to gather sun.
Use the traditional two columns of Sunflowers and Peashooters to defeat the zombies (with the occasional Potato Mine). This level will be a lot easier if the player plants a Snow Pea on every lane to slow down at least one zombie in each row.