This was the most beautiful place we stayed on the South Island - truly breathtaking. The shearing shack is cozy as advertised. It is also very clean, uncluttered, has everything you need for cooking (gas fridge and stove, wood stove, bbq, well equipped kitchen in terms of pots/pans/tools), lots of information on local history and environment and, most important, the views out the front windows are *stunning*.
It's a great spot for kids - there is not much they can get into right around the shack and the inside of the shack is simply enough decorated that you don't have to worry about knickknacks being broken. there's a nice low verandah to sit out on, a fabulous outdoor bathtub.
The drive in from Collingwood is long, on a winding gravel road, but the views out over the tidal flats are gorgeous.
I highly recommend some of the hikes/walks around the farm - especially the paddock loop ridges (I think that is the name - the walk starts behind the woolshed). The beaches are also beautiful.
I would highly recommend this as a getaway. As a bonus we had good cell phone coverage (2 degrees) while staying in the shearing shack.