"I bought this because a month into adopting a kitten, our two older cats were still having problems with her. I sprayed it around the favorite spots and within minutes it had worked like magic on the cat (female, spayed 2 years old) who was having the biggest problems. She went from sulking and hissing to playing and happy. Our other cat (male, neutered, 4 years old) was completely unaffected by it. I couldn't gauge the kitten's reaction, since she had no anxiety.
I will note that neither cat did any better with guests (neither is comfortable with people) while Feliway was being sprayed around the house, even when it was freshly sprayed.
I recommend this product with a caution: It may work miracles, or it may be the biggest waste of money you've ever encountered - it depends on your cat."