It's been a few years since we had a Saw film and with the killer having been dead for the last few films it seems odd that the makers would try to bring him back for one more. But they have and if you're a fan of the series then they have you hooked in, such is our behaviour to not leave a list incomplete; something that that gets easier to do the larger the franchise gets, and I think this is the 8th of 9th film.
I can't give too much away but they do find a way to bring Jigsaw back, credit to them and so we get another assortment of sick traps, some better than others and some odd choice of cameos. One of the cast has already played another character earlier in the series. Also I quite liked what appeared to obvious plot holes turned out not to be the case.
If you haven't seen a Saw film, watch the first one. Don't start with this one.