We saw the inside of some of the ground floor cells in earlier shots. Apparently these were predominantly the solitary confinement cells. The doors opened outwards (see image 13184), at a guess because there really wasn't a lot of room for them to swing inwards.

Prisoners who obeyed the prison's rules might eventually find themselves promoted to the first floor. (Second floor, for American visitors.) Although I don't have measurements to prove it, these appeared to be slightly more spacious than the ground floor ones, though it's more "Hotel room in London" type spacious rather than "Hotel room in Canberra" type spacious. There was at least room for a seat, albeit one that looks far from comfortable, and for the door to open inwards.

The jail audio tour mentions that the cells on the upper levels were shared, but I believe that's the case with the second floor cells (which are noticeably larger) rather than the first floor ones. True, I do believe that these are larger than the ground floor ones but if you tried to stick two people in one of them you'd probably halve the prison population each month because half of the inmates would kill the other half.

However the principal improvement wasn't in the accommodation, but in the associated "privileges"; specifically if you got yourself to the first floor you earned the right to work in the cell yard. Now this would, admittedly, be hard rock and quarry work, but at least it wouldn't involve going slowly insane by being alone and locked in a tiny room indoors with your thoughts for 23 out of every 24 hours.

Also apparently you did get paid for your labour. You didn't get the money "inside", but it would give you something to start your life with again once you were released.