The city is everything frost lol. All the history is in it. Its the main city of old time and when you actually go there you will realize that its very special. I've seen many great cities but Istanbul..... thats freaking higher level in every possible aspect. Dunno, for me all those new cities with modern buildings are like meh, always liked cities with historic parts in them. Istanbul has oriental, roman and many more cultures in it all spiced up with modern stuff. The food...... if someone does not like food there, then its surely they are not fans of food at all. You just have to find nice places to eat because in every large city there are good and bad parts lol. Its not like whole city is shining from greatness. If you are from america then you should forget about McDonalds and see what real pro food is haha
(maybe im biased here a bit because balkan's culture has many turkish traditions in general, it comes from being occupied in Ottoman era and the food is similar to what I eat mostly in my country as well lol)
How much are u going to stay? If you gonna stay at least few days then take time to visit all the historic places like castles, hagia sophia ofc, top kapi, miniaturk (turkey in mini shape) and such things and then at nightz go for the great clubs :D oh and dont forget the ride through Bosporus, you simply can't visit istanbul and don't feel the Bosporus. maybe even visit Maiden's Tower lol.
And ofc when you visit Grand Bazaar.... do not buy stuff there if you don't know how to bargain. Everything you see in that bazaar can be found elsewhere for much less money lol. Or you can start talking turkish and get everything for at least half price
EDIT: just saw you have like 7 hrs? lol. Meh you can't see ***** in that time, maybe then just go around Hagia Sophia place, there are many things there to be seen. Top Kapi, Hagia, Blue Mosque, Bosporus and the bridge and few more things in that part of the city. However if you rush and use metro, you can get to few more places easily in no time