public Guid Guid {get;}

{
  var taskItem = Project.Current.GetItems<TaskProjectItem>().FirstOrDefault();
  // if there isn't a project task item, return
  if (taskItem == null)
    return;

  string message = await QueuedTask.Run(async () =>
  {
    bool isOpen = taskItem.IsOpen;
    Guid taskGuid = taskItem.TaskItemGuid;

    string msg = "";
    try
    {
      TaskItemInfo taskItemInfo = await taskItem.GetTaskItemInfoAsync();

      msg = "Name : " + taskItemInfo.Name;
      msg += "\r\n" + "Description : " + taskItemInfo.Description;
      msg += "\r\n" + "Guid : " + taskItemInfo.Guid.ToString("B");
      msg += "\r\n" + "Task Count : " + taskItemInfo.GetTasks().Count();

      // iterate the tasks in the task item
      IEnumerable<TaskInfo> taskInfos = taskItemInfo.GetTasks();
      foreach (TaskInfo taskInfo in taskInfos)
      {
        string name = taskInfo.Name;
        Guid guid = taskInfo.Guid;

        // do something 
      }
    }
    catch (OpenTaskException e)
    {
      // exception thrown if task file doesn't exist or has incorrect format
      msg = e.Message;
    }
    catch (TaskFileVersionException e)
    {
      // exception thrown if task file does not support returning task information
      msg = e.Message;
    }
    return msg;
  });
  ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show(message, "Task Information");
}

{
  // TODO - substitute your own .esriTasks file
  string taskFile = @"c:\Tasks\Get Started.esriTasks";

  string message = await QueuedTask.Run(async () =>
  {
    string msg = "";
    try
    {
      // retrieve the task item information
      //At 2.x -
      //TaskItemInfo taskItemInfo = await TaskAssistantModule.GetTaskItemInfoAsync(taskFile);
      TaskItemInfo taskItemInfo = await TaskAssistantFactory.Instance.GetTaskItemInfoAsync(taskFile);

      msg = "Name : " + taskItemInfo.Name;
      msg += "\r\n" + "Description : " + taskItemInfo.Description;
      msg += "\r\n" + "Guid : " + taskItemInfo.Guid.ToString("B");
      msg += "\r\n" + "Task Count : " + taskItemInfo.GetTasks().Count();

    }
    catch (OpenTaskException e)
    {
      // exception thrown if task file doesn't exist or has incorrect format
      msg = e.Message;
    }
    catch (TaskFileVersionException e)
    {
      // exception thrown if task file does not support returning task information
      msg = e.Message;
    }
    return msg;
  });
  ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show(message, "Task Information");
}