It's how long mine lasted! Mind you, it's laid on sand which doesn't help.
I do have my doubts about how long it will last, but I've only used it to patch repair existing pointing, rather than starting from scratch. I find it hard to believe that something that easy to use can be as good as the real thing, but I'm rubbish at using a wet mix, it's like watching a 2 year old with play dough.