i have tried the can food from the halo brand. i put a small spoonful of it on a baby spoon; milu sniffed it and made a disgusted face and backed away from it.
i tried it because i saw ellen talk about it before on her show. she said it's human grade and that we can eat it too

(she said, just add salt)
anyways, i have no idea if it is a good food or not!

i think ellen probably became a part owner in the company because ellen is a big animal lover and she wants to help out when it's a good brand that she believes in. i would imagine that she did the research necessary before recommending it and telling everyone that she is a part owner. (because i think that if it turned out to be bad food for pets, she will get A LOT of criticism for it)
that said. ellen is still not a nutritionist, and just because she has good intentions doesn't make her an expert in canine nutrition.