What Are Cats Like?

ICYMI this morning Leo & Rebecca's buzz question was about the woman who does not want to go to her new boyfriend's apartment because he has cats and 'it's not her thing.' I personally have never had a cat as a pet nor have I ever really been around them simply because I am severely allergic. 

Therefore I know nothing about them. I know quite a bit about dogs because I had a couple growing up and have one now but I know they are probably very different. I've been to friends houses and see their cats lounging around or curiously pouncing around but that is the extent of it. If I were to be interested in getting a cat as a pet, what would I need to know?