No it isn't. If you're going to use it or products containing it, I strongly suggest you research this subject for yourself since this is not the place to argue the toss. When you do so, as ever, look to the money.
What is that supposed to mean? Coke (et al) probably make more money per volume on the diet drinks. So now that we've looked at the money, so what? As for health, you've got conspiracy nuts on one side, and a clear link with obesity, diabetes, and tooth decay on the other.