Unreal Engine offers a tutorial specifically for developers who already have experience with Unity. They compare the terminology, tools available and plenty more to help translate the similar knowledge between the two engines.
There is currently 7 different build a game tutorials. They all share many of the same features and components, which end up being re-explained in each tutorial rather than introducing many new features in the different games.
If you are planning on following all of them, this can get repetitive.
C++ is a large topic to tackle, which can be overwhelming for beginners looking to learn it for Unreal Engine 4. It's hard to know where to start, and what would specific aspects would be the most beneficial to learn.
This book does a great job of introducing C++ with the immediate goal of applying it to game development with UE4.
This book is ideal for developers who are looking for an introduction to both C++ and UE4.
Set-up is well explained, and concepts are clearly presented using interesting and helpful examples.
The book is split into two, with the first half teaching C++ and the second half is applying that knowledge to Unreal Engine 4. Though this book is a great introduction to UE4, it has more of an emphasis on teaching C++ so doesn't go too deep into any UE4 concepts/features.
Though published recently (February 2015), it's already becoming outdated. Because EU4 is frequently changing, some of the code provided in the book is no longer accurate.
The author of Shooter Game Tutorials provides a way on his website to request an UE4 tutorial. With UE4 still being quite young, it's not always easy to find learning resources (especially for more advanced topics). The author tries to help out readers as much as possible.
You can see a list of pending requests under the Request A Tutorial form.
Though the course only covers fairly introductory material, it is very well laid out. It follows an intuitive progression, and points out important tips and tricks as new concepts are introduced.
The course provides less than one hour of content and is very introductory, covering the UI of Unreal Engine 4 and setting up a project.
At $9, it's likely not worth the value for most people.