Safety

Considering that I have been to many Europe countries, USA, Russia, middle east and far east countries I will say "YES".  But just like all other big cities, there are districts (mostly the one far away from city center or touristic areas) that visiting them at night by yourself is not a good idea even for local ones . 

Since Tourism is one of the main industries in Turkey , both goverment and Turkish people pay attention for their safety and leisure. There are tourist police in touristic areas and under cover police crowded places. Pickpocketing has decreased dramaticly by years and I haev't heard any from my friends or on news.

This doesn't mean that you should be completely ignore pick pocketers , so keep your valuable items secure all the time :)

Credit/Debit cards is accepted almost everywhere so don't take lots of cash with you.