In my opinion, finding a cheap used plate safe would be a much more secure route. You can often find good quality used safes for less than new entry-level gun safes and some gun cabinets.
"Secure" is a somewhat subjective term, but the product you are speaking of is not a security product and not a good match if burglary resistance is desired. It could work great for child-resistance and keeping honest people out. It could also be a good match for low-value storage of things that you wouldn't be super upset with were they stolen.
Should someone attempt to forcibly gain entry, the amount of time that locking box protects from an attack will likely be measured in seconds rather than minutes. You could always supplement the security by hiding the locking cabinet in a crafty manner. However, if a criminal is able to locate a hidden locking container/safe that uses 10 or 12 gauge walls, I'd recommend operating under the assumption that the container/safe will be rapidly defeated, and that even with layered security there is a good chance that the contents will be stolen (and hence those products provide a very limited degree of burglary resistance.)