I don't have any issues with new builds and I don't have any specific information on any of the developments in Welllington. Rather some advice or info on new builds you need to look at. First and foremost check on the developers and their financials. A couple of new builds in the past (especially in the last few years) in an escalating market have failed due to financial troubles. This meant that the home buyers were left in the lurch and had to wait sometimes maybe years for work to be completed by another builder. I would say that the bigger is the development, the higher is the risk for failure or delay due to financial issues.
There is also a tendency for big developments to cut corners to save on costs and in this way lead to poor workmanship of houses being built or inspection failures. In which case, you need to monitor the progress of the construction carefully throughout the entire time.
I would suggest doing a background search on the development including getting your own lawyer to do some searching on your behalf. You will need a lawyer anyway to purchase the property so make them do a proper search including a title search. Check out the show homes in the development or home buyers who have built homes already in that area. Talk to agents and builders and see what they say. The more work you do, you can satisfy yourself that you have made a good buy and potentially have a good brand new house.