I'd like to be convinced that the system is reasonably fraud-proof but, having been a scrutineer several times now I think there are major flaws. In 2011, voter information was floating around the streets of North Dunedin in the weeks before that election having been stuffed into overflowing letter boxes outside empty student flats... easy prey for collecting false voter ID details to front up and vote at a number of polling places - and a very high chance the valid voter (on holiday at their parents' home up in Auckland) wasn't going to bother going out to cast a special vote.
This election, the easy vote card was not intended to be an ID and people were only asked can you confirm that you are A... B.... ? That card could have been purchased, stolen, taken from persons in care or even legally obtained from the EC under a false name. There are a number of other possible means by which multiple voting could occur with detection of fraud being unlikely. I'm not sure how the holes can be addressed (short of retinal scanning) and it'd be a great shame to require proof of identity at polling places as that would deter many from voting at all. The Easy Vote cards were QR coded and could be scanned in future elections (I think a pilot exercise was done this time, to be checked against manual systems) but in future uses (including online voting - one use of EasyVote) that is only likely to provide efficiency improvements, not markedly better security - apart from detecting duplicate copies.