New gear allows you to get some of the newest features available, and allows you to get the best fit. Rodale's Scuba Diving reviews new gear on a regular basis does a guide for new gear each year, extensively testing all equipment. In any case, new scuba gear which is properly cared for will last through many, many dives.
Things to think about when buying new gear:
1. How much will you
Ask around with friends who have used the gear, try it out by renting it at local shops, etc. Also, most shops will let you try gear out in their pool so you can see if you like it. Chances are that the shop will also rent the same lines of gear that they carry, and some will count the price of recent rental(s) against a gear purchase.
Some exciting new advances in scuba gear:
1. Split fins -offer
drastially reduced drag, reduced air consumption, and increased bottom