Honey locust (Gleditsia) was first noted as a casual naturalization in the early 1990s around Auckland. I have now seen it spreading in several North and South Island urban areas. It is not yet a serious weed species but indications are that it may be a future nusiance. I personally would rather plant kowhai (as a substitute) but if you wish to grow it do so being aware that it may be a future seed source in your area for more self establishment. Also watch out for spines on the trunk which cause serious injuries and infections.