I agree, acting was fine
and I also hate when people say that these movies have no storyline, people just go see them to see jigsaw's traps, which is not true at all. these movies have great plots and everything gets turned upside down every 10 minutes. It keeps you guessing, but you never do end up guessing it, its always a surprise
the only thing that I didnt like about saw IV was the Jeff guy, he was in the movie for less than 10 seconds, yet he was the main character in 3. And never in the movie did it say anything about his daughter, who is apparently trapped in one of jigsaw's games that Jeff was supposed to play, but he got shot immediately after hearing the tape. and no one else heard the tape. so where is his daughter? and who is going to save her?