also: consider the cost!
other than the initial costs of buying the kitten and all of the stuff it'll need (iirc bed, litter trays, bowls, scratching poles, crate etc etc came to about £100)
food / litter (decent food = £10 ish per week, litter £5 per bag every few weeks)
we pay £9ish pcm insurance
flea treatment is £17 every couple of months
neutering (£75 for our little girl) and vet checks / jabs aren't covered by insurance (£40/year)
i know the rspca take in a lot more pets when 'times are hard' as people don't realise how much it costs to really care for an animal!
changes to lifestyle will include getting up when the cat wants you to (ours likes to be up at 6ish) she gets on hubbys chest and meaows till he gets up!
they will claw at carpets / furniture / curtains (may be an issue if you are in rented / care about how your stuff looks)
you can't really leave a house cat for any length of time (i.e nights away)
we had our Ami from about 6weeks of age (she was too young really) litter trained from the start, but she has never been out side, and shows little interest in going out (except the only time she came on heat, just before she was neutered, she went mad trying to escape!)
also, if your flat isnt big enough for a degu, is it really big enough for a cat?!