Got back from IST last night.
I did get breakfast, pretty sure due to being gold since my room was just a regular points redemption booking. Breakfast was okay, nowhere near as good as Conrad Istanbul my only other Istanbul comparison. Room didn’t seem like it was an upgrade. Would have been nice to have a view of the river. It was a large room though.
Taking public transit to get to the hotel you would take the metro from the airport, 3TL to buy a token in a vending machine. You can use coins or 5, 10, 20TL notes to buy tokens. Take the metro to a station called Zeytinburnu (you can only go in one direction as IST is the last stop on the metro line). When you get out of the station via turn style you'll have to go through another turn style immediately if you want to get on the tram so purchase another token (same tokens as for metro). Here you take the T1 tram towards Kabatas. When you get to Kabatas you see that it’s basically like a central bus station out there. One or two of the busses will take you all the way to the hotel but I never bothered figuring out the bus payment system, it’s not the same as metro/tram ie no tokens, instead some sort of prepaid cards. Also all of those busses were jam packed and did not look like they were going to be fun especially when you have a suitcase with you. The one time I did need to get to my hotel from Kabatas I tried to hail a taxi but driver wouldn’t take me on such a short distance so I had to walk, took about a half an hour. Generally I would avoid taking public transportation all the way to/from airport unless you are really trying to be on a tight budget. Expect to pay around $40 for a taxi.
As others have mentioned traffic is horrendous in Istanbul, more so on the road where this hotel is located, specifically that 2km stretch from Kabatas to the hotel and even more so on weekends in the evening. It took over an hour in a taxi to get from Doubletree (right near Grand Bazar) to the Radisson with most of that time spent sitting in bumper to bumper traffic on that 2km stretch. When I asked about it in the hotel was told that this was normal traffic for the time of day. This was at 11pm on Saturday night. When I went to sleep around 3am I looked out my window where I can see the street and traffic was exactly the same, still bumper to bumper in the direction of the bridge.
With that in mind if you've never been to Istanbul and are mostly going to be sightseeing I would recommend staying in Sultanahmet area so you can walk/take the tram everywhere.
I can see wanting to stay in Ortakoy area. Especially if you plan on going out at night. There are clubs and bars right outside of the hotel. One can plan their day to do all sigh seeing during the day then getting back to the hotel and staying in the area at night. Don't expect to go back and forth between Ortakoy and Sultanahmet multiple times in a day, it would be too frustrating at best.