We have just stayed at the Marmara Manhattan for a period of 6 weeks.
I am a nanny travelling with a family, and because of this we were looking for a 4-bedroom apartment/suite in New York City, and found it nearly impossible to find something suitable.
The three-bedroom suite was perfect for our needs - the queen bedroom with ensuite provided a private area for myself (the nanny) and the walk-in-robe in the master bedroom was the perfect size to put the baby's port-a-cot (you could even fit a rollaway bed in there if you wanted) so that he had his own "room" (which was one of our requirements) but was still close to his parents.
I've stayed in quite a few New York hotels, and I have to say that I didn't think it was even possible to get a suite of this size in the Manhattan area. The bedrooms are large and the beds are VERY comfortable, with nice white cotton linen and duvets/doonas.
The washer/dryer in the room worked well, and made doing laundry so convenient and easy. The kitchen has a dishwasher which they provide dishwasher liquid for in a big bottle, which was great.
The heating worked really well and we were in NYC at a very cold time. Water in the bathrooms was hot (which is a good thing).
There are computers (3?) in the lobby for guest use, and they have printers as well, so that you can print out tickets, boarding passes etc, for no charge. There is also a drink vending machine and a snack vending machine in the lobby.
Of course, there were some "not so good" things, but they didn't disturb our day-to-day life enough to be "negatives".
If you are planning on staying a long time and or doing any serious cooking you might need to pick up some extra utensils - what is provided is very basic, we had to buy a decent knife, a cutting board and an oven dish to be able to make basic meals. The standard provisions include steak knives, regular cutlery, plates/bowls/mugs/tea cups/glasses/wine glasses. Two saucepans (1 large, 1 small) and one small frying pan, and basic utensils (egg flip, spoon etc.)
Other reviews have mentioned the noise from the street in relation to the 2nd Avenue Subway project. We were on the 23rd floor and still heard noise from the street, including noise from the subway project starting from 7am. This is easily rectified with earplugs if you are a light sleeper, but be aware that the noise does exists and can be heard from quite high up - also sirens etc. are loud, and there is a hospital across the road so sirens are often frequent. However, I don't think there are many places in Manhattan that you can escape this day-to-day noise, and it didn't affect the children napping during the day so it didn't really bother us. This project is not supposed to finish until 2016.
The window blinds are white and have gaps around the edges, which means that they don't block out all the light, particularly on the northern/eastern side of the building where the sun rises. I struggled to sleep in past 6am on a lot of days due to this, and because the rooms are painted white and have white linen the light bounces around a lot.
The internet was frustrating as there are apparently numerous routers in the hotel and our computers/iPads continually disconnected and reconnected. We spoke to staff a couple of times about it, but in the end we just made do. It wasn't too bad, but frustrating when it would drop out in the middle of an important Skype call/meeting.
In general the property is showing signs of wear and tear, but is clean, comfortable and has very friendly staff.
The staff were wonderful - Dennis and his front-desk staff were always helpful and friendly. The doormen were always friendly and willing to go up to the corner to hail us a cab on cold days. For an extended stay housekeeping came once a week and were flexible with what time we wanted it done (due to children's sleeps). Requests to the front desk were responded to quickly.
Although a little out of the way, the area is safe and has the necessary amenities - there is a Rite Aid Pharmacy on 96th St, just a 2 minute walk away. There is a Key Foods Supermarket on 92nd St, 2 minutes in the other direction. Up on 94th and 3rd Avenue there is a Duane Read, and a CVS up on 91st and 3rd. About a 10 minute walk away there is a large strip of shops on 86th Street between 2nd Ave and Lexington, including Borders, Childrens Place, Foot Locker, Best Buy, Victoria's Secret, H&M etc. There is also a good grocery store called Fairway which sells lots of organic products and also has a good international section. Beware the crowds at Fairway on the weekends though - try and go on a weekday!
There is a good Italian place across the road (Nick's) and if you check out grubhub.com there are hundreds of restaurants locally within walking distance, or alternatively, who deliver.
The "6 local" subway is on 96th and Lexington (about a 10 minute walk - others have said that it is "uphill" but I just wanted to point out that this hill is quite slight, and very manageable). The 4 & 5 train are also on this line (the green line) but they go express and the closest stop is 86th St and Lexington (15-20 minute walk). The subway doesn't go directly to midtown/Times Square but you can change to the NQR (yellow) trains at 59th/Lexington stop. A taxi to 86th Street is only about $6 (plus tip) and a taxi to midtown/Times Square is about $15-20 (plus tip), depending on the traffic. Allow about half an hour to get to the Theatre District in busy times.
Overall I would definitely recommend the Marmara to families needing "space" in New York City, where it is hard to find, and to people not necessarily wanting to be in the busy-ness of Midtown and the tourist areas. The views from the higher floors are gorgeous, and I will miss being able to see the Empire State Building from my living room window!