Re: Personal experience
The study was limited in scope, as all studies are. It was designed only to study productivity in a time-and-motion style.
It was only over a 19 week period, so would not have been able to pick up on any medium to long term health benefits.
There is plenty of existing evidence, obtained by different methodologies, to support the idea that sitting down continuously for long periods is bad for one's health. This study just provides some evidence that standing desks don't negatively impact productivity, thus reassuring any employer that is considering installing them.