mecabq

I have stayed at the W. It's a great location, on a beautiful block just up from the Bosphorous near central Besiktas and within striking distance of the Kempinski and Ortakoy pier.

The location is attractive and convenient to the Bosphorous and taxis, though doesn't offer a lot of amenities right outside the hotel, with activity day and night, the way that the Taksim properties (and Park Hyatt to a lesser extent do). I love the location of the W -- for me it vies with the Park Hyatt as my favorite location in which to be -- but for a first-time visitor, maybe less so. (For perspective, it's about a 10- to 15-minute walk directly down a steep hill from the Park Hyatt.)

It's the typical pretentious attitude of W, with indifferent service. The restaurant/bar (formerly known as Spice Market, but re-branded after I was there) was more stylish than most places in Istanbul, but nothing special once you've seen it and had one (extremely pricey) drink. The rooms are also typical W, with funky layout and comfortable furniture. I didn't really care for the bathroom, although the room that I had was pretty big (though probably an SPG upgraded one).

The Hyatt is a lot more calm, mature, luxurious feel, where the W has the dark colors and "hip" (i.e., aloof) attitude with poor follow-up habits in which the brand apparently specializes. So it depends what you're looking for. You will find many reviews of the W on the Starwood forum, and find opinion quite mixed, like with all W's.