I have to say, the 3D really didn't add much for me. I do like the depth 3D adds to a film, but this didn't feel like a film that really needed it. My Bloody Valentine did a much better job of using 3D in a horro film (ie gore and sharp objects flying at you).
I was also disapointed by the lack of Tobin Bell's screen time. Not much more than a cameo really. About 1 or 2 new full scenes and a few add ons to things in flashbacks. Really underused, espeically with this supposedly being the final film.
Story wise, this is just above Saw IV. The primary goal of the film was to get as much deaths/gore in as possible I think. And then just try to work in a story around it. The main character lied about being a Jigsaw trap survivor and what'da know, he ends up in one. The final trap being the trap he claimed to have escaped from. Poetic justice there really though.
MAJOR SPOILERS BELOW!!!
And ah, Dr. Gordon is back. The character we've all been wondering about since the first film. Well, turns out he survived and ended up as Jigsaw's third (and most secret) accomplice. Wasn't much of a fan of that, but I was it was very satisfying to see him put Hoffman in the infamous bathroom without the infamous saw. That felt rewarding and wrapped up/left open the series just enough. It will be just fine if this is indeed the very end, but they didn't ruin all of their options in case they do Saw 8. But it was a satisfying ending.
Oh yeah, and it was great to finally see the reverse bear trap in action on live victim!