Plenty of scare mongering ! I’ve not been to Istanbul but I’ve watched about 10 hours of YouTube footage of the place this week in anticipation! People just walk around filming all night! It looks good but it looks very very busy with people, but they all seem to be just going about their business.
I’d say the rules are the same as any large European city really, be street wise, watch for the tourist traps, firmly tell anyone who talks to you wanting to sell or gift you anything to fuck off, keep everyone at arms length and don’t find yourself a target by being 15 pints deep down a back street on your own at 4am and you’ll be fine!