We had the senior foster Holly, who suffered from colitis and had to have tylan daily. She absolutely loved Merrick and it was the only thing she'd eat reliably.
You open it up and it looks like human stew
I did a one-hour meeting with Merrick a couple weeks back to learn the details of their food/formula, the representative ate the "Wingaling" canned dog food in front of us to prove it's human grade quality. It was pretty amusing! In the end, Merrick IS human food - just without spices, salt, etc. VERY bland.