This is a GREAT poster, by the way.
The two stories here are one dealing with Detective Strahm chasing down Jigsaw, because now it is personal, and then five people, connected by their traps and their lives, have to try to live together or not. Their traps are all tied to working together, which becomes the crux of their story. We also get the backstory of the Jigsaw apprentice and how he got involved with Jigsaw, which started with a copycat trap. I love the very loaded critique "inferior blade" Jigsaw gives him, and it is paid off in the acting, which is great.
Saw V has some bits I really like and some bits I really didn't. All the flashbacks and the detailing of the apprentice and his interactions with Jigsaw are really great. I very much understand some folks not liking the apprentice's acting, and I certainly didn't care for Strahm, but I like Clayface (our household nickname for the apprentice). I also like the overarching schtick of the test plot, though its actual formulaic-ness ends up forcing characters to alter drastically between scenes in at least one case ... actually, I guess I could put that on the actress and not the writing. The final scene in the test is phenomenal, truly horrific and the best scene of the film. It isn't the final scene of the film, which is also pretty good. You know, the more I talk about this film, the more I like it.
It is also the most cringe-making Saw I've seen yet as there is a sequence that, while it has some build up, the actual damage hit me like a sack of bricks. It was very effective. But once again, I do not feel it was unjustified or glorified. Actually all the traps, except one, are great. That one is awful. Truly stupid. Oh, wait, the first one is also, while a classic and pretty good, isn't as good as many of the others from pure filming perspective. Really, the cinematography in generally is just a little under par.
This film is hard to for me to quantify. It is definitely not as good, but it is still good. Essentially, it just doesn't excel, but it is good.