This is true. I have the 13/i7/512.8GB 2013 model and it gets a solid 8-10 hours doing light work.
Run the "Heaven" benchmark to stress that GPU or run the CPU full blast nd you'll get 3 hours max.
An iPad, iPhone, all the old laptops are all the same way however. This isn't unexpected; you only get long battery life if you're not hitting the CPU hard.
The Haswell tech essentially makes it easier for the CPU to downclock and shut down when doing minimal work. Ivy Bridge and earlier chips aren't as effective at this. It's in the idle periods (which can be as short as a few seconds here and there but can really add up) where Haswell really shines. At full blast it isn't any more power efficient than the older model CPUs.
All of that said, it's possible to do some serious work for a few hours like video editing (not rendering out... that will kill battery) and maybe play some video and write emails and surf and still get a solid 6-7 hours out of it, which is mighty impressive for such a workload.
I also tested just basic web surfing with about 30 minutes of hard GPU benchmarks and still got 9 hours.
Thank you very much for this detailed report.
As an aside, I've been reading that Intel would most likely not release Broadwell in 2014, so the significant performance boost with Haswell-like battery gains are not coming next year. This is good - it means that the 2013 is most likely not becoming obsolete a year from now.