http://users.rcn.com/jkimball.ma.ult...ondEnergy.html
Here is some hard data. This source does agree with Joe that more energy is consumed in order to split the molecules than what is yielded. The difference between those two figures is known as "free energy," which this article says can also be harnessed for whatever we need.
It's not a question of getting more energy back than what we've put in, Joe. Gasoline doesn't accomplish this, yet we're still using it. If it can burn, then it can be a fuel used for something. We just need to find the most efficient way to handle it and go with it.