Upvote:2
I was there last week and have not experience any threats. I would avoid public transportation just in case but, my friends use it everyday and they are fine. If you are going to the Touristic places, I would suggest you to stay away from large groups and try to stay in a smallest group possible as a precaution. Shopping malls are safe as it gets since there are security guards waiting and x-ray machines checking you and your belongings at the entrances. (This has been going on for years, 10+ years actually).
There is no reason to be afraid since, this could happen everywhere. (Eg. Paris, Stockholm etc.) Just be careful while you are travelling and try to be on the lookout for suspicious activities.
Take care of your belongings since small time robbers and scammers would want to take advantage of you. (Similar to Eastern Europe, Italy and Greece)
Enjoy Your Stay in Istanbul.