Eyüp and Ali's place was great for our stay in Istanbul.
It is in a prime location, a quick walk away from İstiklal street and Karaköy, and a tram away from Sultanhamet and Beşiktaş. Despite this, it's in a relatively quiet street so you'll be able to sleep without noise pollution from the busy areas. Keep in mind, İstanbul is a very hilly city so you will need to walk up and down hill to get places and this place is no different.
Regarding amenities, the washing machine and laundry rack is great for those on a long trip and running out of clothes. They've also got a well-equipped kitchen so you can make tea, coffee, or even cook a meal. There is also a hammam in the building basement which you can book in for a private session.
The hosts were good with communication and we had no trouble with contact during our stay. They also had lots of recommendations for things to do in the city if you're ever bored or short of ideas. Eyüp was also so hospitable and came over at 1am to help us with issues with the door.
Overall, a cozy and convenient place to stay to explore Beyoğlu and Sultanahmet.