Stayed this hotel many times (more than 4), usually at Christmas market time.
Tried different room types and have to say that standard room is very small on my opinion and last 2 times i stayed at suite room (which is much more expensive but much-much better).
So the rooms are clean and tiny, the breakfast is good, maybe not huge assortment of food but essential thinks fortunately exists.
I have to say that location of the hotel is competitive advantage, because it's in the heart of the old city and not far from Ko-allee (shopping area) - just walking distance.
So i love to stay this hotel and can recommend it everyone, especially suit room.

Carat is all about being directly next to the Altstadt, directly across from the Carlsplatz Market, and a few minutes walk to the Rhine Promenade. It is hard to find a more convenient hotel to Altstadt ( Orangerie excepted ) that is reasonably priced, but of course not inexpensive due to its location.
Rooms are OK. We had a fifth floor standard room which faced outward with a view of the market. It was not noisy with the windows closed. The bathroom is on the smaller side, as is the closet area. There are no drawers, but shelves, which are adequate assuming you are not planning a long stay. All of the necessities are provided, including a coffee machine and cable TV.
Breakfast is very nice, and goes on until 11 AM for those of us that cannot seem to get out of the comfortable king sized beds with two feather ticks. Very sleep friendly place. The food at breakfast is more than the typical German breakfast, and there is plenty of fresh fruit and vegetables, and a great selection of rolls and bread. This breakfast actually was much better than the Hilton in Frankfurt on a Sunday morning!
Wifi very easy in the room with a code from the front desk and FREE, very unusual for Germany.
ZB

Solid hotel, comfortable beds very clean. Small by North American standards but OK for traveller by themself.
Very good buffet each morning that is included with the room. Selection is varied with lots of fresh fruit.
Location is near the metro station and walking distance to the old town and the shopping district on Konigsallee.
Please note there is no room service.

The hotel is very conveniently located close to the Altstadt and approx 10 minute walk to the "Koe" shopping street, the rooms are comfortable & breakfast is very good.
We booked through Expedia a Comfort Room (a quite room overlooking the Winter Garden). Unfortunately we were allocated room 10 ( non smoking overlooking the "Winter Garten"), which was on the ground floor next to the kitchen. I believe the staff started at 5 am, as we got woken from the noise and did not get a full nights sleep Sunday or Monday morning, which we needed, after a night in the Altstadt and before our business meetings.
I would not stay there again, as I find it unbelievable that this room is let out due to the kitchen noise next door, which will occur every morning from 5am, as breakfast is served 6.30 to 11am (a plus point).