I have no major complaints. Staff at Cargills were friendly and helpful, my room was clean, warm, quiet and comfortable, and the courtyard garden is very nice. The hotel is a fair walk from the city centre, and located in a less-than-desirable student quarter of town, but a small grocery store across the street was a nice surprise. Though the gym is a few minutes' walk away, the trade-off is that it is also much better appointed than most gyms available in other hotels onsite.
I didn't sample the onsite restaurant, owing to dining options available elsewhere in the city. Bar drinks were reasonably priced.
My only real complaint centers on the wifi service. While reasonably priced for per-hour usage, and quite fast, I (and others who require internet access for work purposes, I'm sure) would have preferred a data-charge option like that offered elsewhere in New Zealand (i.e. Cafenet). Moreover, unlike other wifi services I've used, this one continues to charge even after the internet browser is closed (with no warning of this), and must be logged off each time. On one occasion, this entailed losing 10 hours of internet credit overnight (a Cargills staff member was kind enough to give me 4 hours of credit for free); on a subsequent occasion it required 10 minutes of continuous effort to get the logoff screen to load! - minutes, needless to say, for which I was charged.
My stay was comfortable and enjoyable overall, and I'd recommend Cargills for the money-conscious traveler.