If you are reading this I understand how do you feel now I've been there before let me wrap up the whole thing quickly and I stayed 32 days so I got a very clear idea.
You want to know if the apartment is really as good as it looks in the photos, the answer is definitely and super clean as well and plenty of storage and more than enough kitchenware, plus the washing machine clothes iron fridge, TV.... You won't ask for anything else.
You want to know if the location is practical, the answer is definitely it's literally couple of minutes walking from Taksim metro, funicular, bus station you can literally go anywhere in Istanbul with absolutely no problem, about 3 minutes walking from istiklal streaat, tons of restaurants, currency exchange offices, grocery markets and pretty much anything you need is a walking distance from you.
The host Erhan is professional beyond expectations he will know what you need and offer it before you ask, immediately reply to your messages and takes a good care of any issues you might have, gives great advices, we enjoyed many long conversations while drinking Turkish coffee which he makes perfectly, bottom line I wanted a good host and I got a good friend. Hats off Erhan I wish you all the best in the world my friend! Harun don't think I forgot about you, we unfortunately didn't meet but you seemed a nice person on text messages I hope we can meet next time.
About the price, it's extremely difficult to find cheaper and it's impossible to find such price with similar quality of service.
Tourism business is selling satisfaction to a customer and in this Rbnb satisfaction is guaranteed!