Liferoof, the fast-growing San Diego company that was recently acquired by OtterBox, was a pioneer in the waterproof case arena with its highly rated waterproof/shockproof case for the iPhone 4/4S. That model's still for sale and has undergone some small tweaks over the course of its lifespan. The company's Fre case for the iPhone 5 is a bit trimmer than the Lifeproof for the iPhone 4/4S. But because the iPhone 5 is longer than the iPhone 4S (and the case is, too, obviously), it ends up weighing the same.
While there are some other small design improvements, the biggest change is the translucent plastic window on the back that allows you to show off the Apple logo. And while you can access the headphone jack, many headphone plugs won't fit into the jack, so you'll have to use an included dongle (it's easy to lose).
The Lifeproof is still my favorite waterproof case, although it's not perfect. You should be aware that there are plenty Lifeproof knock-off cases floating around and they should be avoided (many look a lot of like a real Lifeproof case, but they end up not being waterproof).
Note: Lifeproof also makes a number of accessories that are designed to work with its cases. These include armbands, bike and helmet mounts, and a flotation accessory.