I recently travelled to Welington for a conference, and spent three nights in the apartment.
It was spotlessly clean, very conveniently located - both for the conference and for getting about in central Wellington, and I found the bed very comfortable!
I can't speak highly enough of the assistance offered me by Sarah (who manages the apartment while owner Sophie is overseas) and her husband Trevor. I somehow managed to leave my mobile phone in the cab on my way from the airport. Sarah called the mobile (which wasn't answered), got onto the taxi company and even visited the city police station where taxi drivers are told to hand in goods left in cabs.
My phone is probably gone for good, but I really appreciated their help and consideration.
Other reviewers have mentioned street noise on weekends evenings. The apartment's in an entertainment precinct, so it's lively some nights. I didn't have a problem with it and slept fine, but it mightn't suit everyone.
Overall - highly recommended. Great people, great place.