Unity can cover most of the needs of game development, both for 2D and 3D. It is particularly well suited to games designed to be played presented and played on web pages, but it can create high-end content as well. Perhaps it would be less suited in high-end games which depend to much of sophisticated lighting effects since Cryengine and Unreal are more evolved in this area. On the other extreme, in the case of very simple 2D games for web pages, like newsgames, simpler game engines probably would be more advisable for a faster production, like Construct (2 or 3) or even Twine (in case of text adventures)
The augmentations and detection of images are pretty good. There are no unnecessary effects. Efficient setup and documentation are pretty good. And most importantly good support from services. We can even use this without deep knowledge about AR because SDK makes it simpler for us to use.
It's actually incredibly easy to use given the complex tasks you have. Once you learn the various windows it becomes second nature. Compared to something like Blender (which I would probably rate as a 2 on usability), the learning curve of Unity is a breeze! The only improvements I can think of would be to streamline some common workflows so you don't have to dig through menus to find them.
I have not had to use Unity's support extensively. This is likely because there is so much documentation and so many classes available for free online. Due to this, there is little need for support. They were very responsive when I requested educational licensing. Setting it up and providing it all quickly.
Unreal Engine is a fantastic piece of software but it has a much steeper learning curve and an arcane, idiosyncratic way of developing software that is quite foreign. Unity uses some similar concepts to Adobe Flex, which we've always found easy and sensible. It is also easier to go to Unity having either a Java or C# background. We also explored using Android Studio and Xcode on their own for AR experiences and that is a suitable option depending on the use case, but Unity is still a great tool for rapid prototyping and even for building finished, shipped apps.
It was easy to understand and it has many examples in their SDK. It has good service support so if you are stuck at anything then you will get the help of team
