My little one was very easy to care for (I'm speaking in past tense because she is at my parents' house now).
Day to day, all I did was clean her litterbox, feed her (one 6 oz can, divided into 3 servings), and play with her. I tried to brush her once every week, but it was more like twice a month. This was more for my benefit than hers. She is a short-haired kitty, but her fur got into everything, and brushing helped cut down on it a bit. A long haired kitty would need to be brushed more regularly.
The things I had trouble with were cutting her nails, getting her in her carrier, and giving her medications if needed. Luckily it was pretty easy to train her where to scratch and where not to, and her claws are pretty much self-trimming (although she does unintentionally scratch me sometimes). We would still battle each other over the carrier and medicines though.
She also has a sensitive tummy, like a lot of cats, and is a regular thrower-upper. At least twice a month, but usually more. It's just sort of an ongoing thing we have to deal with and be aware of.
As everyone has mentioned, cats are no different than any other animals, including humans. They all have very different personalities and quirks, but a lot just depends how they're raised and nurtured. Mine was very quiet when I first took her home--now she meows up a storm. Some kitties are more needy while others are more aloof. They are always a joy to behold though, and absolutely wonderful companion animals. I miss mine so much I actually started crying when I was talking about her today at work
Anyway, it's good to know what kind of kitty you're looking for before you go. Everyone loves friendly, perky lap cats but they are often more needy. I had a soft spot for shy, scardy cats, and that's exactly what I got.