Cruiser bikes generally don’t have any gears and have a fairly laid back riding position – ie. the pedals are positioned well forward from the saddle. They have balloon (fat) tyres and relatively wide handlebars. They are best suited to cruising along the waterfront on the flat as many of the features that make them ‘Cruisers’ make them unsuited for hills. They are generally ridden in street clothes.
These bikes are great for cruising (think weekend sports car) but fairly limited in Auckland where you will encounter a few hills. If you are only planning on owning one bicycle, you may want to look at a city bike with 3 or more gears.