Most people think that the value of a quality gun finish is in the way that it makes the gun look. The wood will look brighter and more polished. The barrel will shine under the light of the sun, and you will not be able to see any marks on the metal. The whole gun will look like it is still very close to brand new, even if you have owned it for a number of years. This will make you proud to be the owner of such a weapon, and you will enjoy showing it off to your friends.
The real value of a good ceramic gun finish, though, is that it protects the gun from the weather. When you go out hunting, the weather can take a toll on you and the gun. The morning mist will put a lot of moisture on the metal, and this can cause rust to start forming in a number of places. If it rains, this can be exaggerated even more. Hunting in the winter may cause the gun to be covered in snow and ice, especially if you are waiting in your stand for hours on end.
If you decide not to get the custom gun coating put on the gun, the water will cause a lot of damage, especially over time. You may be able to go hunting once in adverse conditions without seeing any problems. Maybe drying the gun off will be enough. If you keep doing this, though, you will start to see rust around the joints and the places where the water can pool up and sit. This can make the barrel weaker, which can be dangerous. Even if it does not weaken the gun, though, it will make it look worse and it will not function as well.