Its probably as safe as any other hormone replacement.
A lot of women I know have had problems with it though. Coming out of place, falling out entirely, when having sex, etc.
Not everyone is the same when it comes to medication and not everyone that it works great for comes back give a review. A lot of reviews online are based usually on people who had really hard times with meds. So trying to get feedback is kind of hard to do, if that makes sense.