PlayMaker is a Finite State Machine with a visual editor. It is the first plug-in you should get because you act quickly create behaviors wit the visual editor and the action browsers introduces you to all the power of Unity quickly.
Ranked in these QuestionsQuestion Ranking
Pro Easy to use
You'll need to put more time in learning Unity + Playmaker compared to something like GameSalad. But once get hang of it and familiarize yourself with it's possibilities. It's quite easy to use.
Pro Elegant state-based visual scripting
Instead of a single "if this then that" event list which can become very cluttered beyond the most basic behaviors, PlayMaker gives each object a list of states where only certain events are triggered, and performing an action also changes state.
This allows for a clean, simple visual representation which helps break complex logical structures into smaller pieces, making them easier to understand.
It basically can do same things as scripting in Unity.
Pro Third party plugins support
A lot of third party plugins have support for Playmaker. Playmaker team also invest time to add support for a lot of third party plugins.
Con Limited tutorials
There are not a lot videos with Playmaker tutorials. Official text tutorials are also quite limited. Even not every action has a description on an official wiki.