Is a tobacco-free and nicotine-free e-cigarette safe to quit smoking with?

I've quit smoking and besides wearing a patch I am using the smokenv e-cigarette to quit. This model is completely free of nicotine, tobacco, tar and carbon monoxide as it's non burning. I know it's better than a real smoke but is it ok to puff on this thing alot for the first few weeks? It comes in flavones and releases a harmless water vapor. So is it safe to use fairly heavily