This is a very easy to use platform, I think this is very well organized, you will always get support when you need it, specifically in the iPhone App.
There is a Mentor Course, for those chosen that have been good at some courses.
You can find almost everything (talking about courses), of lots of topics and categories. It's simply amaizing.
You can learn a lot, even if you don't pay for the certificate.
Some courses videos and documents are not up to date.
If you want to learn via online, with a good quality and in a low cost... this is your platform.
I have learned a lot.
You can get courses and even a Specialization Certificate supported by a recognized University around the world with this Platform.