Very interesting topics, and is indeed a good transition to upper levels. I had problems with some available resources I had where I felt that the difficulty is below my level. This is exactly what I needed, a challenging difficulty but not difficult enough to discourage me.
I discovered the extra materials on Tobira's website a bit late, so it's also good to review it. Don't forget to check it out, folks!
The only negative thing is that the anki deck with audio is not working on my mobile app. But I can live with it, I use other resources for anki.
It has a lot of grammar (upper intermediate level), a lot of interesting reading material and everything is explained in Japanese, so it is definitely not for beginners.