Over the last 50years I have had a series of cats. One of my current 2 was found as a kitten running around in Fulham High Street - he is still a bit of an outdoor cat (I have a cat flap). The other one was adopted from a friend as an adult. I have previously adopted cats from Battersea Dogs and Cats Home and taken in other stray cats. Each cat has a different personality, none have been problematic - other than one which developed health issues. There has only been 1 cat which I didn't like - he was too clingy - and he is now very, very happily re-homed with a friend.
I have never had a pedigree - although used to look after 2 siamese when the owner was on holiday. I have had a half siamese (noisy!!!)
If you adopt a kitten you will need a dirt box, etc. If an adult and have a cat flap, you would need to keep the cat in for at least 2/3 weeks to acclimatise it.
The benefits of a cat are enormous - one kept me sane when having a horrifically bad time at work - it knew when I had had a bad day and would come and curl up on my lap - normally, it didn't.