Deployment – Unity exports to pretty much every possible platform: Mobile, Consoles, PC, VR, you name it, with minor porting and platform specific features needed.
Take a look at the full export list here.
Flexible – Unity is not limited to a specific type of game. Although 2D games are harder and less intuitive to make with the engine, everything is possible if you’ve got the technical capabilities.
Ease of Use – compared to other engines, such as Unreal and CryEngine, Unity’s learning curve is rather low and the engine can be picked up by anyone, although it is recommended that they have some prior knowledge in programming and/or game making.
Community – Unity has one of the largest – if not the largest – community when it comes to game engines. There are resources all over the web, ranging from simple beginner-friendly tutorials to more advanced and complete tutorials. If you ever stumble across a problem you can’t solve, there are tonnes of places online where you can ask. See resources for links.
If you’re planning on making a small mobile game, Unity probably isn’t what you’re looking for – its build (app) sizes are huge. An empty scene in Unity results in a 10Mb mobile application.
Unity’s source code is not available to the public. If you find an engine bug, the only thing you can do is submit a bug report and pray that it gets fixed. It is possible to license Unity’s source code, but chances are it is unnecessary for your needs and extremely hard.
If you make more than $100k gross per year, you need to purchase a Unity Plus license (Up to $200k gross) or a Unity Pro license (Unlimited gross).
Unlike similar engines, such as Unreal Engine, there are many more advanced features that don’t come out of the box, mostly regarding graphics and post-fx. You need to either make these yourself, or you can head on over to the Asset Store and look for an already made solution.
If you want to export to iOS or OSX, you need to xCode to compile your game, which can only run on a Mac. (Hackintoshes may or may not work, depending on your machine).
