Full Inspector naturally extends the Unity Inspector so that it supports dictionaries, structs, interfaces/abstract classes, properties, and generics. Full Inspector also provides a much better list/array editor along with annotation based comments and tooltips. Not only that, but Full Inspector seamlessly integrates your favorite serializer into Unity, whether is be Json.NET, protobuf-net, BinaryFormatter, or a custom solution.
Full Inspector is extremely easy to use. All you need to do is derive from[backcolor=rgba(255, 255, 255, 0.6)]FullInspector.BaseBehavior instead of[backcolor=rgba(255, 255, 255, 0.6)]MonoBehaviour and you're good to go! If you override [backcolor=rgba(255, 255, 255, 0.6)]Awake, just call [backcolor=rgba(255, 255, 255, 0.6)]base.Awake.
Custom inspectors that support all .NET types are easy to write; the process is similar to creating a PropertyDrawer, except that PropertyEditors are much more powerful. They naturally give you support for generics and inheritance.
Full Inspector includes all source code. It is highly commented and designed for readability.
Full Inspector works perfectly in Unity Free. Mobile also works well; just make sure that your serializer supports it (BinaryFormatter and Json.NET (from the Asset Store) work great on iOS / AOT platforms)!