I will not be covering the feature set of each tool, since this is published on their websites. I will instead be talking about the reasons I feel these tools are useful to a consultant/designer like myself, and why you should get both for your own toolbox.
Playmaker (https://www.assetstore.unity3d.com/#/content/368) is a tool allowing you to visually design logic for use in your games.
nGUI (https://www.assetstore.unity3d.com/#/content/2413) allows you to visually build menus and work with menu based visual effects.
PlayMaker NGUI Scripts (https://www.assetstore.unity3d.com/#/content/10257) is a bridge program allowing you to use Playmaker and nGUI together. NOTE: While this software was not totally up-to-date when I started using it to bridge the above two tools, it has since been updated by the creator. This by itself should be a selling point, since many stop supporting their tools in unity soon after making them. Kudos to merlin981 (http://forum.unity3d.com/threads/192544-PlayMaker-NGUI-Scripts)
These three tools allow me to not only make my menus visually, but then to connect them to programming logic without ever having to ever write a line of code. While I am an advanced C# programmer, I can say from experience that being able to flowchart your menus and gamestate logic is a good thing, and well worth the $200 I spent on these tools.
And before you programmers out there tune out this review, it should be noted that PlayMaker can tie into your own code with little effort. Playmaker, at the very least, can send SendMessage signals to any script you like. Truth is it can do a LOT more than that, but you can look up PlayMaker and read that elsewhere.
None of these tools are effortless to use. They take a willingness to learn how they work, just as Unity does. In exchange, they offer you a better (not necessarily quicker) way to design your project and menus. One that allows you solid a design and debugging process that can be modded much easier than traditional coding alone.
Combine that with PlayMaker's efficiency and nGUI single drawcall for rendering, along with the fact they are fully compatible with both android and iOS, and you have a solid winner.
I've been building a toolbox for Unity for a while now, and I have to say that I can't really see myself regretting these purchases any time soon.