Spend a couple of days in Berlin with the family. We are 5 with a 2 year old girl and a baby which was the main driver to find a hotel that allows all of us in 1 room. This mercure offered it, our son was sleeping on the sofa, they added a baby bed so that we were all taken care of.
As mentioned by the other reviewers, beside the huge room incl balcony, the main selling point is the location, very close to Kuhdamm and the theater at the Kuhdamm as well as subway and S Bahn station. Also history of Berlin museum is close by and plenty of restaurants.
Checkin was no issue, they were prepared as they knew we were coming. We reserved for 4 nights. Unfortunately we got only 1 roomkey (card), they mentioned they have not got enough. It would improve to get more cards that travel parties can also get more than just 1. We had to take the lift to the top floor. The lift is big, even refitted with a new flooring to make it look better. However, the lift is old, as the hotel, so you need to wait for a while to use it, it is really slow. Our room was at the end of the corridor, kind of a walk. Also the walls were not in best condition, some fungee on the wall already. However, this is only true for the corridor, inside the room everything was fine but the A/C system. That one was working but dripped a lot of water on the carpet.
Beds were all comfortable and the bathroom was good too with good waterpressure. Cleaning the room took place in the afternoon, which was a bit suprising. Coffee and tea was in the room included and the TV with German and other channels was available. We also used the internet, when connected it was all fine.
Breakfast is served in the morning. Food selection was the normal with some surprises. There was a very nice selection of cheese (above average) and also some special hot dishes I did not know before. The room itself was spacicous and specially the staff was really nice here, they took a bit care for our kids. What helped is that they had a kids corner around here for them to read or draw.
Reception staff was friendly and funny, also made it enjoyable for the kids.
Checkout was also fine, received a billl without problems.

The location is a stone throws away from Kurfuerstendamm subway which is fantastic! However the WiFi is absolutely terrible where most of the times it was very slow and would drop out. I did make mention this to the front end staff and they didn't do anything to act upon it or follow it up with me. Also, my stand in shower in the bath would leak water on the top corner of the floor which can be a hazard. Apart from that, it was an ok stay for a first time traveller to Berlin.