A surprise package
The gameplay and the story of the are pretty unique. Your house is being invaded by Zombies, so you'll have to plant your defensive plants in such a way as to prevent the Zombies from proceeding any further. And to plant these plants you need sun points. You have various kinds of plants, like Pea Shooter, who shoot peas at the incoming zombies. You also have sunflower, which can keep providing you with sun points. Then you have "wallnuts" that stop the zombies from proceeding any further. In each level the zombies come in two waves - the first one is pretty weak and it allows you to utilize this time in building your strong defenses while letting your weak defenses handle the first wave. Then when the second and final wave comes, you'll be prepared for them. With each level you complete you get a new plant that you cant plant.
The music and graphics of the game are pretty cool. I specially love the cartoonish way in which the entire game has been portrayed. For example, the name of the seed company that provides you with the seeds is "Bloom and Doom company". The zombies look like they have been taken out of some comedy horror cartoon like Adams Family. Even the plants names are punned like "Sunflower" - provides you with sun points, WallNuts - acts as a wall, etc
You'll actually start loving all this after you start playing the game, and I assure you it is as addictive as any other game.