I also stayed at the D-Cube about 2 years ago.
Things I remember I liked:
- Lounge and Lounge Service - the Staff was amazing
- Breakfast and the views from the Restaurant
- proximity to subway station (even though it is not very central, we could conveniently get anywhere we wanted)
- views from the high floors (the hotel only starts on the 18th floor or so...). Definitely great to grasp the enormous dimensions of this city.
Don't expect a Suite upgrade though. Apparently they only have very few suites.