The answer to this question comes down to personal preference! Generally speaking, if you are a healthy adult, your cat sharing your bed is unlikely to be harmful. However, not everyone wants their cat in bed, no matter how much they love them, and that's OK too!
It would be advisable to avoid allowing your cat to sleep in a bed if you suffer from a suppressed immune system that may make you more susceptible to infection, if your cat has any signs of infection or if you are very unwell yourself. Allowing your cat to sleep with babies or young children is never advisable due to the risk of accidental suffocation.