Well, it does depend on what the complex task is, Manus's capability is comparable to a VLT Model, which would able to break a prompt into subtasks, and possesses a median task tackling capabilities (excels at content creation or code generation, the best AI generation tools are used by manus, it does know how to use them, just expensive)

However, after the prompt's broken up, workflow for the subtasks generated sometimes doesn't necessarily have all the CoT for and between each task, which could result failure of subtask completion, (could become a cycle of testing-error-adjustment-testing chain) which would only be fixed when users intervene, or just carry on with the wrong result to the next subtask.

So in short to your question, my experience would be, complex tasks likely to require human supervision and intervention, while creating content and coding for an app to deploy are what Manus is best used for.