I've owned two, one for only 6 months and my current one, for about 2 years. Both were purchased small and this last one came from an established tank. It was in the tank for 7+ months before I actually saw it eat because it's extremely cryptic behavior. As I have added more angels to the tank it has become a lot more "social". I now see it out and about very often. It is a pig as well, scarfing down all types of foods with gusto.
As a whole they are very difficult to keep due to their shyness and their inability to either adapt to captive food or the fact that most are cyanide caught. My first one looked great, saw it occasionally, and it ate, but it just perished one day.
Good luck, they are a beautiful fish!