If your dog is doing well on the dog food you're feeding, and you and your vet are happy with it, there's no reason to change. Many high quality kibbles are an excellent, balanced way to feed. It's not that raw feeding is necessarily "better"--it's just different. Both ways of feeding have pros and cons.
Raw feeding is an alternative to kibble (or a way to supplement kibble) where you feed your dog a "natural" diet made up of raw animal parts--the kind of things a wild dog might eat. Chicken, turkey, venison, pork, beef, fish, etc.---all fed raw, with the bones.
It can be expensive. Most raw feeders buy meat in bulk to save on costs, and feed cheaper cuts of meat. Chicken parts often make up a big part of the diet, and that can be pretty cheap. It would cost around $2-3 per day to feed an average GSD a raw diet. Perhaps a bit less if you're a really good bargain shopper. At that price, raw feeding is comparable with some of the more expensive kibbles.
If you're interested in learning more, take a gander at all the threads in this forum.
You can also read about it, and see what meals look like here: