The cat I was looking after last summer LOVED these, more than other brands I tried for him.
My cat doesn't care for them at all, though. She'll lick the slimy parts up for a few seconds, but then the rest sits untouched until it needs to be tossed. She'd rather just have her kibble than consume this.
So it's really dependent on the cat whether this is a hit or not. I will say that going grain-free is not necessarily of any benefit to your pet unless there's an actual medical reason for it. Cats absolutely require meat protein and are obligate carnivores, but that doesn't mean that things like grains and some vegetable are at all BAD for them in small quantities.