I could write a lot about how nice this place was.
Long story short: we arrived 19 people instead of the 18 we'd told in advance. No problem for Evrim and Erdem - they just made another bed. We even arrived much later than we told initially and Erdem was very pleasant and welcoming. He even showed some of us to a kebab place at 1.30 a.m. and paid for us because we had no Turkish lira.
Communication was very clear and the fixed airport transfer was very nice!
I can recommend this place to everyone looking to visit Istanbul. It's spacious and the location is very nice, close to the Galata Tower, nightlife, restaurants and metro so you can easily visit other parts of the vast town.