Congratulations! You now have enough information about Cocos2d-x to produce awesome 2D games. First sprites, then actions, and now particles.
Particles make everything look shiny! They are easy to implement and are a very good way to add an extra bit of animation to your game. But it's very easy to overdo it, so be careful. You don't want to give your players epileptic fits. Also, running too many particles at once could stop your game in its tracks.
In the next chapter, we'll see how to use Cocos2d-x to quickly test and develop game ideas.