I bought a six pack a couple weeks ago. It's a nice addition to the SN family, and goes for the typically inexpensive SN prices (about $7.99 a six pack where I live, sometimes on sale for $6.99). Overall it was an enjoyable beer, but to be honest for a buck or two more I much prefer the Weihenstephaner Hefe.
The SN Kellerweiss will be a beer I'll pick up again if I can't find Weihenstephaner or Paulaner. It's a notch below those fine beers, but a decent substitution if you can't find those, or want to save a dollar or two.
I think its a fine rendition of a german hefeweizen and has a good balance of phenols and esters - my only critique is that I would prefer a touch of hop aroma to make it a little more complex. It's fresh and unpastuerized, unlike many german imports of the style, and a buck or two cheaper per six pack as well. I would find no need to even look at the german imports when I want to pick up some bottles at a beer store - wouldn't stop me from having a Weihenstephaner or Julius Echter on tap though if both were available.