Though the area is a bit dicey at night, in truth, I've never felt unsafe, though for solo women, it might be a caution.
Getting a room toward the back where it is quieter is more expensive! The traffic noise takes some getting used to, and it just hard on the ears for a sound sleep.
Also, I don't know if it's the carpeting or ???? but there is a noticeable odor to the place....not terrible, but some serious disinfectant could eliminate it permanently. I've read other threads that mention the same thing, so it needs to be called to management's attention.
I've booked at Grand Sagcanlar for each of my 4 visits to Istanbul for largely the same reasons: location to everything I care about is EXCELLENT! I'm a walker and prefer to roam Istanbul on foot, so it's proximity to the sea, shopping, restaurants, buses, metro, trolleys, all historic sights, museums, etc. can't be beat.
The staff knows my face now, and do all they can to make sure I have what I need. Few speak English and are able to give advice, where to go for shoes, leather, etc. They are helpful always and make my stay there enjoyable.