Overall I enjoyed this course. A few points if you are thinking of studying for HSK 5 or have just finished HSK 4.
1) You will need to know all of the HSK 5 and some HSK 6 vocab in advance, before you start the course. This course does not focus on introducing new vocab, instead, you are expected to know it. If you don't know the vocab, don't bother, it's going to be far too difficult.
2) The most useful sections are on listening and reading. Grammar and sentence structure sections are incredibly boring and useless and full of mumbo jumbo liguistics jargon. If you are already around HSK 5 level, you should already know the grammar basics so can safetly skip these sections.
3) It's free. Therefore 4/5.
