We visited New Zealand and Australia for 3 weeks in early 2008. Haast was by far the WORST stop on our itinerary. We decided to stay here because it was about halfway on the drive from Greymouth to Queenstown. Big mistake!
There is nothing to do here. All the motels are overpriced dives, about $100 for a cheapo room that does not even compare to a $40 Motel 6 off the highway in the USA. There are a total of 3 restaurants for dinner, but don't be late as they close by 9 or 10pm. Did I mention that the restaurant prices were absurd? $26 for fish and chips!!! No joke. The local store closes at 7pm, and the gas station with minimart is also not 24 hour. So if you need milk for the baby (as we did) you could be up a creek.
But the worst part, aside from the fact that there is nothing to do here, is that the mosquito type bugs will eat you alive. We were still suffering from these bites a week later after we returned to the US!
As with all places there is one good thing: because there is so little ambient light (Population 60) you get a great view of the stars in the southern sky at night. And our motel owner was very nice, even if his place was overpriced. I mean we have paid less to stay on the Sunset Strip in LA - and this is about as far as you can get from that.
Needless to say there are better places to stop on this road. If we could do it again I would have stayed overnight in Franz Joseph Glacier or Fox Glacier (the former is a nice town) or further up the road towards Queenstown.
Avoid Haast at all costs.