Let me first say that I was disappointed to see that they were casting for Saw 6 on VH1.  Not because it was on VH1, but because it was happening at all.  The first Saw was a great movie and the next two installments were entertaining.  However, just because a franchise is making money does not mean that the producers should continue to stretch an already very thin story.  It seems that the plot is getting awfully tired.  In an attempt to throw in new twist after new twist, the story has become really watered down.
Keeping Shawnee Smith as the heir to the Jigsaw murders would have been a great place to stay.  She did a great job in the 2nd and 3rd and I really don't understand why the change was made.  I get that they needed some new twists, but again, the story has just been made so thin that it is ruining the whole franchise.
The only positives that I noted in V were that the traps are again very creative and the gore is top notch, along with the acting.  The pendulum scene in the beginning kicks off a great series of new traps, each a little more inventive.  From the pendulum to the "bathtub circuit completion" to the table saws at the end, the traps are great and the gore keeps with the high quality that people have become accustomed to with the franchise.  Unfortunately, this and the acting are absolutely where the positives end.
The acting is once again strong with a crew of actors with quite a bit of previous work.  However, no amount of professionalism on the part of the cast can save this franchise.
In V, we learn that a crooked cop is an apprentice of sorts for Jigsaw, dating all the way back to nearly the beginning.  Another cop is close to busting the whole case wide open, forcing the crooked cop to try to lure him in and end his chase for the killer.
We do learn that the crooked cop has a legitimate issue with the man killed by the pendulum in the beginning.  This man killed the cop's sister and probably had it coming. 
The movie then picks up in a similar fashion as the second installment, with a group of people locked away trying to survive.  I am going to leave it at that for now, as the movie is relatively new and I want to limit the amount of spoilers here.
Bottom Line:
The franchise, in my opinion, has been ruined by stretching the plot a little thinner each time.  I may watch Saw 6 only to review it.  I certainly have no great desire to see it otherwise.  The first movie, and even the next two installments, were quite worthy and it is shameful to continue ruining them.  If you want to see some quality gore and creative traps without much of a story, this one may be ok for you.  Had this one been a story on it's own it might have been ok. 
Maybe the producers and Lion's Gate should actually try to create something new instead of continuing to beat a dead horse?
This one gets a 5 only because of the traps and great gore.