It has not been a problem for us. We moved from the UK last July into a new top floor apartment (6th floor) I don't know what the temperature is like compared to lower floors but with the aircon on not an issue and being from the UK the summer temperatures here are very very extreme. We have reflective glass on the windows which I assume helps, seems to be fairly standard with the newer buildings.
It has not been a problem for us. We moved from the UK last July into a new top floor apartment (6th floor) I don't know what the temperature is like compared to lower floors but with the aircon on not an issue and being from the UK the summer temperatures here are very very extreme. We have reflective glass on the windows which I assume helps, seems to be fairly standard with the newer buildings.