Can someone explain to me the point of the Saw Series?

hmm...now I can't wait to watch them I actually haven't seen them and haven't been at all interested in watching them but...my husband went out and bought the whole set all 4 of the movies so...I need to make some time for them! I think from what I hear about them they make you very angry at the victims while at the same time you feel sorry for them and...the movies (I've heard) end w/o actually having an ending! so they kinda leave you hanging! anyways I really need to watch them they've been laying around my house for a couple weeks now!