I am starting to see differences!
I have already mentioned poop, of course, and that is still true: much less, and less stinky. All of the cats are starting to look shinier, and this, too, is no surprise.
One thing I was not really expecting was the fact that the really fine, soft hair behind my long-haired cats' ears is not tangling as much. Same with Bandit, and that was a real problem with him. He would start getting snarls there in a matter of days, and he HATES to have his ears messed with. I've never really had a big issue with the cats getting "eye boogers," but I have had it with him, and that seems to be improving, too. He has less of that discoloration that you see so often under the eyes of white dogs. It's not all gone, but it's better.