TOTALLY worth seeing in the theater IMO (at least a matinee..lol). I just got back. This was definitely just as good as 1 or 2. They incorporated the first and second movie into it very well which made the plot more interesting, and as usual, the ending is always killer (no pun intended).
If you liked 1 and 2, 3 is a no-brainer.
If you want pointless gore, see 'Hostel.' Saw'* gore is not pointless IMO. The plot is the point of it all. It'* proved to be a very twisted and clever series of films.