I have a slightly smaller Stack-On, it's OK. Keep in mind most "gun safes" are really no more than "residential security containers". A TRUE safe, that's fire resistant and break-in resistant enough to actually do some good, will cost many thousands of dollars and weigh a ton.
If it's big enough for your needs and it's what you can afford, go for it! People can, and do, argue endlessly about "gun safes", but the bottom line is you need to protect your goodies and very few of us can afford $10,000 for a "real" safe. Just be sure to put it in a dry location, where it would be very difficult for a thief to get to, and bolt it down securely.
I've heard of thieves tying onto safes and pulling them right out through the wall of a house, how you gonna protect against that? You can only do what you can do. ANY safe is better than NO safe, IMO.