These vacs are meant to be used on a daily basis - you program it so it vacs when you're away and it switches itself on automatically and does a couple rooms at a time. Having that in mind it will keep your house clean as it vacs every day, where normally you would do it once a week. It has contra rotating brushes, so yes, it will lift the cat hair.
Good points: very quiet, simple programming, works when you're away, hoovers under the bed
Bad points: doesn't do stairs, won't hoover very tight corners (where it can't fit), small dust bin
It's best for bigger opened space rooms where there's not much things lying around.
I will be getting one as I have a cat too and just can't be bothered vacuuming the house all the time. But I wouldn't spend more than £200 on it, and Roomba seems to be the best of them.
Regards
Chris