Why choose Unity?
There are a great many game authoring tools, engines, and frameworks that you may have explored or read about before investigating Unity 3D. What makes Unity an attractive option? Here are a few selling points:
Large community: You want to avoid going with a tool that only you and some middle-schooler in Siberia know how to operate. Unity has a very large user base, which makes it much quicker and easier to find answers to your questions, and to find online videos, tutorials and books like this one that explain new concepts. A large community also implies that development on the software will continue. Nothing's worse than training on a tool that is later abandoned.
Social proof: The fact that large companies have bought into or partnered with Unity Technologies bodes very well. Electronic Arts has purchased a site-wide license, and (at the time of this writing) two out of three major console manufacturers have struck licensing deals with Unity to spur development on their systems.
Bang for the buck: If you ever "go pro", you'll want to invest some pennies against a full version of Unity. While it's not chicken scratch, the amount of power and the number of options you get from Unity vastly outweigh the cost outlay.
Market success: On any given day, a survey of the chart-topping iOS games turns up a proportionately large number of Unity-developed titles. Unity is being used by a great many developers to create games that survive in the market, and thrive once they're there.
Customizability: The entire Unity authoring tool can, itself, be authored. Developers can create their own windows, buttons, and panels to add to the Unity authoring tool, which has led to a very active secondary market called the Unity Asset Store, where you can download toolmakers' creations to make your development experience even better.
Multiplatform: It mystifies me why people pour so much energy into tools like XCode, which can target exactly one platform (or maybe two? I honestly don't care enough to check). When faced with such a diverse marketplace, it's a savvy developer who chooses a technology that targets multiple platforms.
