4 stars only because there's no washing machine (though Mehmet said there's a laundry service near the house) and microwave. Otherwise it's a good apartment. The host is really responsive and his tour guides are good (at least food guide). If you feel cold, there's an opportunity to turn on heating.
For those who prefer calm places, just note: the apartment locates in quiet area, but it's 4 mins away (walking) from the most touristic epicenter in Istanbul: Aya Sofia, Blue Mosque - which is great, but going from the metro station to home you'll meet many people and highly likely scammers etc. Be careful and Just take it into account and the trip will be fine.