A topic that does come up frequently. First of all to really be safe from theft, I suggest you just send all your coins to me. If a crook breaks into your house, they will find nothing. See how easy that was.

Safes are really not to smart if your worried about theft. As it is delivered half the neighborhood will see that and wonder just how much money do you have laying around.
Friends, neighbors and even relatives may see it when visiting. As they mention it to others the amount of money you have in there will grow exponentially until you have millions hidden away. That will inspire someone.
A gun to you or your family's head will open that safe regardless of how big and strong it may be.
Unless that safe is air conditioned, items inside will be exposed to the same air for as long as you keep it closed. Humidity will just stay there. If you keep it in a basement, every time you open it, humidity will enter.
During a fire all will usually be safe? Not really. A metal safe will get hot, the plastics inside will melt. Cardboards will smolder. All that on your coins. Newer cents made with Zinc will probably start to melt.
A neighbor went on vacation some time back. While gone a moving van pulled up. Nosey neighbors asked the movers what was going on. They said the people that lived there liked it so much where they were at the decided to move there. Naturally when the vacationers came home and found an empty house they were horrified. Neighbors could not remember the movers. OH, the safe. Yes the movers took that too and it was bolted to the floor. AHH, an alarm system. The movers took that also.