直接访问数据成员是一种不好的做法吗?

我记得一位教授告诉我以下是不好的做法。但它使代码的单步执行变得不那么乏味。我只是说说利弊:

Friend Class MyClass
 Private isEmpty As Boolean
 Public Property IsEmpty() As Boolean
  Get
   Return isEmpty
  End Get
  Set(ByVal Value As Integer)
   isEmpty = value
  End Set
 End Property
 Public Sub MyMethod()
  ''//Is this more correct:
  If Me.IsEmpty() Then
   ''//Do something.
  End If
  ''//Is this bad practice?:
  If isEmpty Then 
   ''//Do something.
  End If
 End Sub
End Class