The comments, from the design watchdog's review panel, have blasted the firm's handling of the living space in a recent report.
The proposed scheme aims to create a 30,000m 2mixed-use development including office and retail space, restaurants and a boutique hotel, as well as residential units.
The report stated: 'We continue to find the residential layout to be the least convincing aspect of the scheme. As well as being an exciting place to live, it should be a good one also.'
It continued: 'We think the combination of difficulties in planning flats at the inner corners of the cube - single aspect accommodation, potentially overlooking one another across the courtyard - and the claustrophobic nature of the corridors might make living in this development an uncomfortable experience.'
However, project architect Frances Gannon is unperturbed by the comments and is certain the designs are the best way to meet the needs of every aspect of the development.
She said: 'We are confident the apartments are going to be great. This building is utterly unique and is a proper, mixed-use building, and it can be difficult fitting together all the requirements.
'Because it is a mixed-use building, the floor plate is larger than it would normally be in a residential building, and this means we can't create double-aspect apartments.
But they will be comfortable units, and there will be no problem of people seeing into other people's homes, as the smallest distance across the courtyard is 20m - much larger than any normal street.
'We are very confident we are providing the best design,' she added.
The practice is aiming to have the project on site as soon as January 2007.