* It's ideal for treating nonsense hunger. That is, hunger which does not impose a concrete penalty for ignoring it. Emotional eating and social eating both fall into this category. \o/
* It's very bad for situations where the appetite signals hunger, and without eating, penalties such as headache, stomachache, and irritability ensue. Those need a different solution.
* It doesn't have a user-controllable off switch. That means you can't, for example, allow yourself to eat a full healthy meal and then use the device to quell urges for snacking. It seems to get stuck in nibble mode.
* Drastically reducing food intake without improving the quality of food would greatly increase dietary illnesses. Most American food is high in calories but pretty low in actual nutrients. Cut the food and people who already aren't getting quite enough vitamins will suddenly be getting up to 40% less. No, you can't simply replace those will pills, because bioavailability is much lower with pills than with actual food.
Do you think doctors will care about these factors? I don't. I think they'll use the same bullying tactics they already do with other things, and once this device becomes available, it'll be "Get this implant and stop being such a pig, or you don't get any health care." Which will predictably make people's health worse, because many people already avoid health care because they don't wish to be abused about their weight, and that undermines health. But not as much as letting people hurt you, so for many folks it's a valid trade, even if it's less good than what they should have with good care. This is regrettable because the device sounds ideal for treating a subset of overeating which is pretty common.