Are C# regions a good thing??

Well, I'd say it depends. If you use regions to logically group your code in your class, then it may be a good thing 'cause people come to your class and see something like

public class MyDummyClass : IMySuperInterface
{
   public MyDummyClass(...)
   {
      ...
   } 

   #region Properties
   ...
   #endregion

   #region Utility
   ...
   #endregion

   #region Implementation of IMySuperInterface
   ...
   #endregion
}

In such case it may increase the organization of the code inside your class. I wouldn't say it increases the readability of your class since it's just a matter of code reorganization.

Many times however you find people using regions like

public class MyBLClass : IMySuperInterface
{
   public MyBLClass(...)
   {
      ...
   } 

   public IList ReadAllOrComputeWhatever(...)
   {
      if(parameterA >= someNumberOrString)
      {
         #region Check for blablabal
            // 30LOC+ hidden here of CC 10+
         #endregion
         ...
      }
   }
}

...then regions suddenly aren't that nice any more. I find that a lot of people actually use it for hiding their ugly, "smelling" pieces of code which would highly have the need of being refactored. I think this is very much related to this here.

So...

• logically grouping: good thing, though it depends on preferences (I personally don't like it that much)
• code hiding: bad practice. Sign of a code smell and you should consider to refactor it.
  

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