New is definitly not always better IMO. Guys have been killing deer dead with bows older than I am for years. They kill as just as well as a new bow. Every year manufacturers come out with new products that may or may not be better. Thats where we come in, the buyers. Sometimes companies do come out with technology that is "better" than previous designs. Cams designs are moving forward all the time making the bow more efficient and quieter. Same goes for riser and limb designs. Bowtech has made a name for itself with the parellel limb design. It does a great job. Hoyt, same way with the riser deal. It does its job well.
Basically, it depends on what you want a bow to do. If you shoot only Mathews bows and don't see the big advantage to the newest lineup, don't buy, I wouldn't. But if there are breakthroughs in the design that truely do make the bow better than what you have and you want it, go for it.
Me, I'm settling down myself. I am going to go on a three or four year rotation. It seems thats about how long it takes these days for a new bow to really be a big difference from latter years models.
I know, I say that now.......wait till next year.