I had the plastic one used in an exterior location, which isn't a good idea – was always finicky and difficult. The metal one seems to be more reliable. I wouldn't trust it somewhere I cared greatly about security, but combination locks aren't generally great in those cases.

One of the difficult parts is telling anyone else how to use it. Up-down-left-left-right, but only after you pushed it in to reset it? With a standard combination lock all I have to tell someone is the combination, and one of the great parts of a combination lock is that you don't need to copy a key or anything in order to delegate opening it.

So in my opinion it's only an okay lock.