When comparing GameSalad vs PlayMaker + Unity3D, the Slant community recommends GameSalad for most people. In the question“What are the best 2D game engines?” GameSalad is ranked 63rd while PlayMaker + Unity3D is ranked 79th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Cross-Platform
Pro No-code editor
Pro Has a Windows(.exe) version on par with Mac
The Windows version is now upto date with all the features of its Mac sibling.
Pro Multiple publishing platforms
Can create and publish games for iOS, Macintosh desktop and laptop computers, Android, Kindle, Amazon FireTV and FireTV Stick, Windows 8 and Tizen devices.
Pro Gamepad support
Gamepad support is available as of 0.13.3.
Pro Free standalone viewer app allows instant, live mobile device testing
The GameSalad Viewer is a free app available for iOS, Android and Kindle. Once installed on your mobile devices, you can deploy and test your GameSalad games live on any mobile device running the Viewer that is on the same local network as your dev computer.
This even allows Windows users to test their games on iOS devices without a Mac device and without any complicated code signing or provisioning profiles.
And, you can even take your games with you -- once loaded onto your mobile device, a history option caches recent games on your device without any connection to the dev computer.
Pro Allows you to focus on the logic rather than code
Since the user mainly uses menu options there is very little code needed to be keyed in. This makes the code very easy to read and understand.
Hence there are many help videos on youtube
Pro Extensive community of seasoned professionals for support
Extensive community of seasoned professionals in all disciplines (graphics, game design, animation, physics, music, video production, marketing, etc.) producing tutorials, videos, publishing tips, free templates and who are willing to answer forum questions and help newcomers.
Pro Powerful expression editor and functions
Allows you to create expressions on par with LUA (it's back end-language).
Pro Custom collision shapes with JSON support
Allows you to import JSON data for custom collision shapes to use with Gamesalad's implementation of Box2d physics.
Pro Easy to publish
Software prepares your app so you can just send it to Apple. All my games are reviewed with no problems.

Pro Drag and drop editor
The drag and drop editor makes GameSalad very easy to use, no programming experience needed.
Pro Great engine
Very quick to learn and great for making games. Community is very open and helpful.
Pro Easy to use
You'll need to put more time in learning Unity + Playmaker compared to something like GameSalad. But once get the hang of it and familiarize yourself with what it's possible to build with them, it's quite easy to use.
Pro Provides access to a huge list of assets through Asset Store
For those developers who can't afford an artist, or aren't skilled enough to create their own art, Unity features an Asset Store full of a wide variety of free and paid assets that can be easily added to your game. The Asset Store has more than just music and art. It also has code and modules that can be added to your game such as unique lighting or GUI systems.
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.

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.

Pro Powerful
It basically can do same things as scripting in Unity.
Cons
Con Bad editor
There is no scene zoom, search boxes, or snap to grid. There is also no ability to focus view on the actor or use folders for file structure.
Con Expensive compare with others
There is no free version any more and it is very expensive compared with other engines.
Con Poor editor performance
Especially when you're working on a big project.
Con No scripting language or SDK
If a needed behavior is not supplied by GameSalad, there's no way to add it.
Con Product is suffering - Lacking company leadership and no voice from corporate
Some customers are currently in a holding pattern from the lack of support and messaging from GS corporate. GS is currently unstable and developers are waiting for another update that has been going on from 2015.
No word or message from GS corporate about timeframes or deliverables.
You can read the ongoing discussion here.
Con Product is in Limbo - company is lacking developers
Con Doesn't support Windows platform (*.exe)
Doesn't support Windows platform (*.exe)
Con Comparatively high learning curve
Although C#, JavaScript, and Boo have extensive documentation available online, it could still be difficult to wrap your head around the library and Unity's component based system.
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.
Con Performance could be better for 2D
Performance can be a real issue with 2D games. Unity 3D is actually a 3D game engine, and drags a lot of overhead with it.
For mobile, one could never achieve the performance of more specialized 2D engines with Unity3D.
