Cats are stupid, much, much stupider than dogs - either that or I own deficient ones and have only ever met deficient ones...
I don't quite understand the point of cats, mine are substitute dogs. One sort of fulfils that, but she's Siamese. I can't train her though, she learnt her name and she can tell when food is coming, but that's about it. She does play fetch and is very affectionate though, she'll sit with me for hours and come running when I call her.
The other one, the more cat like one, she's sweet enough when she wants to be and I'm quite fond of her, but I don't see much of her (she's either out or sleeping) and you can't do anything with her that you want to do when you want to do it, she freaks out at the oddest of things and just looks at you vacantly if you try and call her for anything.
Based on the catty one and other people's cats I'm not sure what they do as pets, they seem to mostly live in your house, eat your food and ignore you apart from when they randomly demand attention at awkward times.
I've come to the conclusion that they're mostly ornamental. They do that very well.