We had an okay stay at Umut's place.
The good stuff: the location of the apartment was great, it is 3 minute walk away from Taksim square and Istiklal street. There are many cute shops and restaurants around. Umut and his team were very responsive and made our check-in smooth.
The bad stuff: the apartment really doesn't look like the pictures any more. Everything on the pictures is still there, but it looks like it has been through a lot. There are random stains on the walls and the sofa in the living room; the wooden furniture has a lot of scratches. The towels provided also had some stains on them. If you plan to stay here, lower your expectations regarding the appearance.
If you are planning to work remotely for a bit from this apartment, be aware that wifi is spotty, it keeps disconnecting every couple of minutes which makes it impossible to have online calls.
There is very little wardrobe space, which is inconvenient for longer stays.