There are two buses travelling on a circuit approximately 1/2 hour apart. Each bus stops at each location every hour, thus you can stop at a location for 1/2 hour, 1 hour or more and a bus will be by to pick you up in 1/2 hour intervals. The bus provides a taped narrative of points of interest in view while you are travelling that give you additional familiarity with the area. We found all the drivers to be friendly and informative. In the busy season (Oct. 15 to April 30th) there is a second route touring an additional 6 sites.
Sites at which the bus stops are as follows: Kelly Tarlton's Antarctic Adventure, Holy Trinity Cathedral, Auckland Museum, Parnell Rose Gardens, Parnell Village (trendy shopping area), Sky Tower Hotel and Casino, Victoria Park Market, and the American Express Viaduct which is the home of America's Cup Yachting. The auxiliary high season tour includes Mt. Eden, Auckland Zoo, Museum of Transport and Technology, Imax Entertainment Centre and the Auckland Art Gallery. Separate journals on some of these are attached.
This is a good starting place for your time in Auckland. In addition to the sites you stop at it will make you aware of other points of interest.
If you are staying in the downtown core, several of these places will be within walking distance. We bought the two day pass, but could have got by with one. The problem in planning is you don't know how much time you will spend in some places such as Auckland Museum.
The main benefit of the Explorer bus is that it quickly gives you a feel for the layout of the city and the narrative is quite good. It also eliminates the need to study city maps and try to plan ways to get where you want to go. For those on a tight budget you would probably find the city bus lines will get you everywhere much cheaper if you are willing to put in a little time to figure out the routes.