This apartment is quite new, well equipped and very modern. The location is sensational if you wish to be near Darling Harbour. I stayed for 4 nights, part-vacation and partly to attend a work conference. I could easily walk everywhere, felt safe enough in the city, and there is a good Coles supermarket for supplies only a few minutes walk north of the apartment.
To get to Darling Harbour you can walk north and around by Pyrmont Bridge, or go across the road to the Novotel and downstairs from its carpark to cross at the railway station instead. Parking on Murray street is accessible during the week (meters) or in the Wilson carpark across the street (secure but expensive).
As other guests have said, the downside of the central location is noise from the motorway flyover as traffic builds into the city weekday mornings from 6:30am. As I had to get up and going, I was OK with the early start, but bear it in mind if you wish to sleep in. My stay did not include a weekend, so can't comment on nightclub or other noise. As a suggestion to the owners, they could replace the stylish (but useless) modern blinds in the bedrooms with heavy (more functional) curtains that may block the noise a little better?
The MadeComfy team who run these apartments are very responsive and good communicators by phone and SMS. Two sets of key collect/check in instructions were emailed to me, which was a bit confusing and contradictory, but the MadeComfy person was able to swiftly sort it out over the phone, even on a Sunday evening check in, which was really appreciated.