As someone who has teaching experience but not experience teaching English, I found that this course was a great opportunity to learn about what it's like to teach English abroad. There are videos of classroom sessions which are great examples, and you can practice writing lesson plans with detailed and timely feedback from the instructors. You can also revise the lesson plans you submit based on instructor feedback.
This course is a bit more expensive than some 120-hour online TEFL courses, but it seems more thorough than average, from what I researched. This company also helps with document legalization, which is rare for TEFL companies, and a major help if you're going to China. The course is mainly focused on teaching children, but there's lots of helpful teaching theory relevant to any age group. I was able to finish the course in a little under a week, but I made it my main focus. The exams are low-pressure because you can download the readings and reference them as you take the exams.