They gave me a sample to try before I actually opened the box, so I could return it if he didn't like it. He did, though. Liked it a lot, actually. At first he was kind of like, "What's THIS? Do I eat it?" It took a couple licks for him to get used to it, and then he licked it clean and wanted more. I got the "Thrive" one.
I plan to use it as a supplement, mostly for variety. I just don't go for this nonsense that dogs can eat the same thing every day and not become bored with it. From the reading I've been doing, it sounds like a lot of people are abandoning that myth.