First off, I would like to mention that I found the episode slightly difficult to follow, the first time I watched it. I would recommend watching it at least twice to fully understand the story.
The case was fairly interesting, but I don't particularly enjoy Tobias Fornell too much, and the episode was centered quite a bit around him.
The episode did have one great element, which was to "expect the unexpected". Really, absolutely everything in this episode was unpredictable, and this did very well.
However, I did not understand the ending and how Fornell was still alive.
Overall, not my favorite episode, but it is still worthwhile. It is interesting, but not overly exciting and it is rather unpredictable. Good episode for me, not a great episode.