First off, I'll mention what I thought when going into this anime. I was expecting this side story to be exciting and at least somewhat near the level of Puella Magi Madoka Magica. However, unfortunately it did not come close to reaching that level for me. I felt that the plot was quite random, and the central idea of the actual anime wasn't captivating and didn't make much sense. Throughout the anime there is barely any character development in any of the characters except in the last episode. Furthermore, there were so many new characters being introduced, in addition to some of the original ones, that I couldn't remember all of their names! This aspect was a little exhausting, especially because most of them didn't stay throughout the whole story and disappeared for some episodes and came back. The ending was also quite confusing for me as I didn't end up understanding it.
On the other hand, I enjoyed that the side story stayed true to the art style and made connections to the actual anime, Puella Magi Madoka Magica. The idea of witches still maintains throughout the whole anime and the soundtracks, particularly in the fights, were pretty good!
However, despite these positive aspects, I don't think they are able to make up for the lack of planning and plot of the side story, hence why I gave this 6 stars. Finally, I would recommend this anime if you really truly loved the original anime and would watch just about anything related to it, but if you aren't a superfan I would not encourage you to spend your time watching this side story.