My wife and I stayed at the TITANIC hotel for our first anniversary. I booked the standard room with breakfast and spa. The hotel interior was impressive and the rooms were clean. The bed was superb - I have never slept on such a comfortable bed! The breakfast was great: lots of fresh options for food and coffee, made-to-order omelettes and sparkling wine. The spa was nice in a way with a steam room, a sauna and a resting area, though there was no pool which was slightly disappointing.
I have mixed feelings about the location. The area is central, clean and safe, and next to some attractions. At the same time, it is a bit dull compared to the overall bohemian vibe of Berlin. There are much more interesting, restaurant-filled areas in the city. Luckily, public transportation stations were close.
Overall the staff was super friendly and polite and made us feel welcome. We only had one minor setback: in the first night, we got back to the hotel around 2.30 am and planned to take a shower and head to bed; however, we noticed that the bathroom lights did not work. We were asked to pack our things and move to another room. We were not very happy with having to re-pack and move in the middle of the night when we were already super tired, and had to argue with the staff to get a satisfactory room upgrade for the inconvenience. We eventually got it, and were happy with the compensation.
Overall we were very pleased with our stay.