I've stayed at the QBIC before for IBC at the RAI but I don't expect to be back.
There's a lot to like, it's conveniently located for the RAI, easy to get to on the train, metro and tram, breakfast is ok and the wifi works well and the water pressure is good.
However, the thermostat in my room would not get the air below 24 degrees all trip, despite it being 18 or under outside. I checked with the front desk (who were lovely) and it was correctly set to try to get to 20, but it stayed crazy warm. I was given a fan, but the experience was bad and my sleep suffered a lot as a result.. and ultimately that is what matters.
Bits of the room are starting to look a lot more worn than a few years ago, rust in the bathroom etc., although the room was very clean outside the wear & tear.