A good question, and the answer is… it’s as safe, or unsafe, as any other big city in the world. It’s as safe as you make it.
What we mean is this: if you walk round the city, dripping with gold and watches, fifteen cameras round your neck, flashing thick wallets, leaving bags behind and looking and acting generally gormless and loud, then yes, it’s not safe and you are asking for trouble.
If you carry just what you need, know where you are going and behave in a sensible and alert way, you will be fine.
There are things to watch out for: pickpockets, aggressive beggars, people doing the three card trick, buskers gathering a crowd, human statues, you know the kind of things. Just be careful.
You do not need to carry your passport with you so keep it in a safe place. Keep a photocopy. Have a list of serial numbers for phones, cameras etc. Don’t leave things lying around unattended. Don’t get dragged in to conversations with strangers. Don’t give beggars money. Shop assistants and waiters should not be taking your payment card away from you.
Have travel insurance.