c# - Public Fields versus Automatic Properties

We're often told we should protect encapsulation by making getter and setter methods (properties in C#) for class fields, instead of exposing the fields to the outside world.

But there are many times when a field is just there to hold a value and doesn't require any computation to get or set. For these we would all do this number:

public class Book
{
    private string _title;
    public string Title
    {
          get{ return _title;  }
          set{ _title = value; }
    }
}

Well, I have a confession, I couldn't bear writing all that (really, it wasn't having to write it, it was having to look at it), so I went rogue and used public fields.

Then along comes C# 3.0 and I see they added automatic properties:

public class Book
{
    public string Title {get; set;}
}

which is tidier, and I'm thankful for it, but really, what's so different than just making a public field?

public class Book
{
    public string Title;
}