Rafael Jovine’s review published on Letterboxd:
You know? I get it. For a film series in which the only thing people cared about was creative and deadly traps, this is a complete letdown. Furthermore, the movie throws twist after twist, moving things around and fitting our new villain's apprentice into and tweaking the over-arching story that people have been following for five years now. And for what? To fully introduce a character that many SAW fans hate.
Like I said in my review of the fourth film, I liked Petterson's Strahm, and it was nice to follow Hoffman's journey to becoming the man who takes a totally different approach to Kramer. In contrast to John's attempt to do something "good" and use these deadly traps to teach people a lesson, you see the much more realistic and sadistic consequence of this in the form of Hoffman. His tendency to seek pain and be a full-blown serial killer is one of the most interesting things about him, and this film shows you why. While Kramer's film comes from a supposedly place of "understanding" and sick, twisted goodness, Hoffman's is full of pure hatred. Clearly this was the way to go and makes you wonder why John let him go through with it, though if I remember correctly he didn't and he had a backup plan. But let's not get ahead of ourselves.
All in all, even though the cast of players and the game itself is largely insignificant and feels almost tacked-on, at least we got a nice cat-and-mouse detective and origin story, that personally had me invested. Another departure for the series in some respects, and one that nicely pays off, in my opinion.