The course is rather disappointing. Videos are short. They give you an intuition, why something works but don't go much into the details. When teacher said "Now you are an expert in transformers" it sounds like a mockery. The course material is split into four weeks, however you can obtain certificate after spending a few days.
Homeworks won't teach you much. For you to understand, by now the most hard exercise according to course's Slack is to write a function with model and input tokens as input, which should predict next token. It's body contains only 8 lines of code, some of them is already given, your task is well explained.
Trax, a deep learning framework, that is used in homeworks might be a great framework, but not for learners. All you need to do, is just to pick a layer, put it in right place and
voila. But instructions makes a situation even worse. It is so detailed, that you can just copy a code from instructions, paste it into your code and obtain a working solution. Sometimes you should look at documentation just to see the argument's name. You won't have to think about dimensions, you won't have to think about structure of a model. When you decide to write a transformer from scratch with Pytorch then, you will struggle hard, but the price is much deeper understanding.
Would I recommend taking this course? I think, that course team did a nice work to provide you an overview of the state of the art techniques in NLP. Some references are amazing. So if you treat this course like intorductory, you could take it. But don't expect too much. When you are said, that you will "build a chatbot using a Reformer model" take in mind that the crucial skill to do it, is just a copy-pasting.