Here is the view for applying MM2H from a Malaysian point of view, whether to do it yourself or your agent it depends on how much it cost for you to travel to Malaysia to submit the documents compare to the fees charged by the agent. If you so happen to visiting Malaysia you might as well do it yourself. Pretty much you need to visit Malaysia twice; one for submitting all the document on hand, second to get the visa upon approval.
Each visit should be at least a week (5 working days) if you have all the proper documents ready. The approval rate is high as long you are financially strong. Don't worry if you see your application status remain the same after you have submitted the document.
I knew an applicant who got the approval letter yet the system still shown pending approval. The system finally change the status to approval 3 months later after receiving the actual letter. I guess there are some backlogs.
You can refer to the official MM2H site for the steps, and some google will give you the ideas and advise on what to do. I wouldn't say is hard, and with Uber or Grab, car sharing facilities it is easy to move around.
You must be patient, if you think you have a good supporting document, very high chance your application will approve. It is just a matter of time. Minimum 6 months ..