California Natural is a very limited ingredient food, and does have high card content, as rann already pointed out. However, I think it serves a purpose.
I recommend Cali. Nat. for people trying to sort out possible food allergies, or dogs with really REALLY sensitive stomachs. I've had my Beagle on it for over a year, and in is 13 years of life, it's the one single food he has actually done well on, so that works for me.
I think it is better than its competition line Wellness Simple Solutions, which is still good, but even more grain heavy.
On the other hand, it is very carb heavy, so unless your dog needs a "simple" food long term, or you're going through the process of pinpointing possible allergies, I don't see any need for a dog to be on this food as their main diet, when there are other foods with less carbs, more meat content, and higher protien that if your dog can handle, are better.
Agree with Corgipaws, its way too grain heavy in my opinion, but some dogs have super sensitive bellies or are allergic to foods with multiple ingridients, so this may be the only thing that works. I think its slightly better then natural balance since it has a bit more protein ( not by much though)