My partner and I had a stellar time and it was nice to call Karen's little apartment home for eleven days. It had spectacular views of Lake Wakatipu and was easily accessible (by car) to Queenstown village. If you're walking, the walk to town is roughly 20-25mins downhill, so the walk back is uphill and tiring! A car is a definite, unless you like long walks uphill.
Karen replaced our towels every day and changed the sheets twice during our eleven-day stay. The apartment had comfy couches, a small TV (which nobody in the apartment used, but thank you for providing it), plenty of brochures for local attractions, a big bathroom with a washing machine and clothes-rack. The kitchen was well-stocked with cooking pots and other utensils, bar some minor (ultimately non-essential) details like scissors, cling wrap, and cooking oil. For short and especially longer stays, a microwave would be an excellent and greatly appreciated addition - so much of the cheap and easy-to-make food in supermarkets is microwavable, and for our relatively long stay it would've been awesome to be able to make meals ahead and reheat them easily. Of course, it's not essential, though I am sure it would be treated like a godsend from your upcoming guests!
We only encountered one minor problem during our stay - the stove seems to have only two settings: off, and ten! The top right one has also stopped working, but we made do and it wasn't a hassle at all :-)
Thank you again for the accommodation - we had an absolute blast.