Composure Liquid MAX for Dogs and Cats, 7.6 oz

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Vetri-Science Laboratories
Pros: cheaper than herbal essences per oz IF it works for your cats
Cons: unappetizing, didn't work for my cats, went bad
I bought this off of someone's recommendation on this forum.  I had recently gotten a new cat and my resident cat was growling, hissing, chasing, etc.  The smell is a little milky.  Neither of my cats ate it when I put it in their food.  I tried syringing it but my cat struggled so much and the amount I needed to get into her was so much that it made it unrealistic to do everyday.  After about a month, it started to smell off!  It smelled like sour dairy.  I had hardly used it at all, and was very disappointed.  The instructions did not say to keep it in the refrigerator or anything.  I also checked reviews on Amazon and apparently it goes bad for other people too. I didn't see any changes in behavior either.  I know a lot of people swear by this, but for us personally, it wasn't a good fit.  
Pros: It worked well with my boy
Cons: not very palatable
My boy had a case of redirected aggression brought on by a neighbour's cat outside my cats' enclosure.  He would keep attacking my girl.  One of our TCS Advisors recommended this product and it has been invaluable.  After a week things have settled back into the normal state of sibling rivalry instead of all out warfare :-)  I've been told to keep in on it for some time then gradually taper off.

The only issue I have is that my cats are incredibly fussy eaters and he noticed it and avoided his food, so I've had to mix it with only the most desirable food..  I started by giving it to him straight, or mixed with his probiotics using a dropper, but it wore very thin with him very quickly.  But the effort of getting it into him is definitely worth the effort