This is a more challenging area than the beach just to the south, so it is really only suitable for intermediate and better kitesurfers and windsurfers. It's still a relaxed and friendly spot, and anyone with the experience will have a good day here.
The beach is very small, but it's a nice sandy surface and never gets crowded even on the warmest summer days. Water temperatures are very comfortable in summer, easily into the high 20s, while in winter they will dip to the low teens.
September to November provides the best winds, when almost every day will give 20 knots or more as it blows in from the west or the south-west. For the rest of the year, summer and winter still offer the chance of decent days with wind speeds between 10 and 20 knots fairly frequently. The bay is a big area, 5 km x 5 km, and the water is shallow almost all across it. The best time to catch it is when the water is at the high tide position, and the surface will be either flat or choppy depending on the strength of the wind.
There is plenty of parking available right next to the Marina, just a couple of minutes walk from the beach. There are also public toilets here and the odd food outlet, while the nearby town of Beachlands has a few shops. Auckland is just 40 km away and is where most people base themselves before travelling over here.
This is a very safe area, your only real hazards are the Marina itself and boat traffic entering or leaving it.