I've taken a few shots with this & love it, although the photographer in me has observed a few flaws - the sensor still has a limited dynamic range (obviously a phone camera doesn't replace an SLR) which results in clipping of highlights & detail as well as a couple of other minor things such as not being able to use the flash at the same time (although given the way the HDR works on the iPhone it isn't surprising you can't use the flash).
For me the greatest thing about the feature is you don't have to stand there taking three photos - the camera just takes the one (so it seems) and hey presto!