You can really feel a difference between your chinese level before and after taking this course. If you passed HSK 5 and followed this course, it is not likely you will pass HSK 6 after it as the vocabulary you need to master is really a lot. However, this course gives you a very complete introduction to the HSK 6 exam, and it helps you getting familiar with the structure and requirements you will have to fulfill.
What I liked the most were the listening, reading and grammar classes, and especially the last weeks recaps about these things were very useful with a lot of examples taken from past exams, important tricks you can use and emphasis on the vocabulary. I also liked how the whole course was in Chinese, so it has been a long listening exercise from start to finish.
I liked less the writing section, the teacher sounded stiff and repeated the slides quite hurriedly and mechanically, and very few practical examples were given. It gives you a knowledge about how and what to write but you only actually do it twice.
I feel every week assignment could have included some vocabulary list to memorize and letting you use those words in a sentence, so to increase the amount of new words that you familiarize with and master after the course.
The main shortcoming with this course, in fact, is the fact that listening, reading and writing all require you to know a lot of new words to tackle them successfully, and they cannot be all included in the course due to time limitations. I would suggest to take this class after you started preparing for HSK 6 rather than starting it after HSK 5 like I did, because you can understand most of the content in it: reading and listening has been most of the time a work of guessing from the context rather than understanding the whole thing in its entirety, and also you need to have a solid grammar background. I would definitely recommend this course, it makes the HSK 6 exam less scary for sure :)