I have one. Its a digital Eheim unit. Easy to program and dispenses various types of dry foods. I can say I haven't had an issue with it and that it seems to work fine. I only use it for short, one week or less, trips. Extended trips like our Bahamas excursion this summer, I hired a local kid to feed the tank.
Be advised that feeding dry "flakes" and pellets can and will make your Phosphates go sky high is a very short period of time. I have seen it first hand in my tank. Do a good WC before you leave and do another as soon as you return to minimize the effects.