A room here starts around €1,100 a night and what you're paying for is the water: the hotel sits directly on the Bosphorus, and the views from the rooms and the breakfast terrace are the thing almost everyone mentions first. The building itself, by Tihany Design, backs that up with heavy marble and rooms that run bigger than the Istanbul standard. The staff turn up by name constantly in the reviews, Berk from the butler team gifting İznik tiles, Beyza setting up a surprise tea service, Deniz remembering a coffee order overnight, and that kind of anticipation is what separates this from a hotel that's merely well-located.
It isn't seamless. The kitchen is the recurring weak point, with slow room service, an overcooked Adana kebab, and a poolside burger that arrived cold after an hour turning up across multiple stays. A few guests also describe being charged the full stay plus a large buffer at check-in with refunds slow to land, and at least one case of a damaged item settled badly. Housekeeping misses (a leaking bidet, missing chargers, no bathtub in some rooms) show up often enough that they're worth knowing about before you book, not just bad luck.
Book it for the location and the spa, both genuinely among the best on the Bosphorus, and go in expecting the restaurants and billing to need a bit of patience. If round-the-clock polish at the dinner table matters more to you than the water view, the Four Seasons Bosphorus is the one people compare it against. For most travelers here, the room, the staff, and the strait outside the window make the case on their own.