We had a great time at Eren's place. Check-in was very easy and his apartment is in an amazingly central location, steps from the Galata Tower, Istiklal, eateries, etc.
The place is very charming, spacious and has been renovated. It's an older building so it's by no means perfect but it's very comfortable and has everything you need. The kitchen is decent, the fridge is big, etc.
Be prepared for steep stairs - no elevator here! But it's a good workout if you're into that. The view from the roof is nice too.
The only negative: the laundry machine is a little temperamental. It boiled some of our clothes on a 30 degree celsius cycle (they were literally steaming when the run finished) which wasn't a great outcome! That said, we tried later on the "quick wash" setting and it was fine. Use at your own risk basically! We messaged Eren about the issue and he replied immediately and was very apologetic. Communication was great all round. We did have a small issue with the heating but Eren immediately sent over someone to fix it and everything was great after that.
All in all: a great place to stay in the centre of Istanbul. We'd stay again in a heartbeat!
Thanks again for a great week!