the pak'n'save in the kilbournie shops area of wellington is quite nice actually, we've had a generally pleasant experience there. I like the fact that they are more forthright with what's imported and what's local and the prices are excellent compared to New World (the other grocery chain we've checked out so far). We've actually found some good deals on produce at the small vendors along cuba and in Newtown tbh, so we've split up our shopping. More of a hassle, but overall cheaper and some of the stuff has been better quality.
But no, The Warehouse reminds me more of Walmart than costco, and pak'n'save only has the food aspect of Costco. Simply not enough market to support that size of business I don't think.