What you get are two double beds in a roomy vintage wooden shed with an outside seating area and wood burner. Showers and toilets are in a modern shared block. If you're not a nature lover or have a dust phobia then forget it. If you're after an enjoyable stay with a difference then book. We were visited by a deer and a couple of bats chased away the bugs at night.

Things to know:
Showers require four quarter coins (something that wasn't mentioned on checkin)
Cleaning of the cabins doesn't seem to extend to under the beds or the interior wall frames. Ours had thick dust under the beds and on the structural timbers - something that a vac once a week would have addressed. It's a shed at the end of the day but sheds can still be kept clean.
Cabins have what UK readers will know as a Yale latch on the doors and very basic catches on the windows and fly screens. They're not 'secure' by any means. It's a big shed.
Ours had one interior main light, an outside light and one double power socket (one of which fed a bedside light)
Gents loo has only one cubicle, which caused a bit of queue huffing from some residents.
Eating choices at the restaurant (the only catering for some distance) are a bit limited. It gets busy - we had to wait for a table and waiting staff seemed stretched. There's a food store that's open until 6pm (9pm on Fri, Sat, Sun) with basics - including fire wood - if you've the means to self cater. The log burner has an oven space if you're feeling adventurous.

After the tents of Yosemite my expectations were low and I was blown away by these cabins.

Solid floor, carpets, four wooden walls, a lockable door, electricity, bed linen, windows, chairs, a dressing table and mirror. This all seemed the peak of luxury.

Each cabin has its own parking and small under cover deck area with a wood burning stove. You are allowed to cook and eat at your own picnic bench. No bear lockers are necessary. Food and toiletries need to be in the cabin, not the car, at night.

The shower block was large but there were very few showers (two for each gender I think) and toilets (just two again) despite the huge amount of space that the building took up. In September this didn't lead to any big queues but I guess it could be a different story in the summer.

We used to tent camp but now prefer to not rough it. We stayed in one of the many tent cabins which is actually a single-wall small wooden structure. Only a few have private baths. We didn't get one of those. But we always need to use the toilet during the night.
Since we were already staying in Kings Canyon we made a point the day before to stop at Grant Grove and survey the cabin selection. Some are farther away from the shared bath building, and the paving isn't in the best condition. A challenge in the dark at night. We requested a specific 'tent' cabin, explaining our reasons. The front desk was most cooperative.
Our little cabin had a single overhead bare light bulb which did the job. We were pleased that everyone around us followed the "quiet-time" rules. We had a peaceful night's sleep and I had the pleasure of watching a young buck wander through the area early in the morning.
The Grant Grove restaurant is only a short walk away and the food was good.

Its not luxury accomodation, but its more than adequate and the fantastic surroundings more than make up for any let down with the cabin. Bed was nice and the park was nice and quiet at night, we had a cabin with its own shower and toilet, I believe that to be worth the extra money, rather than dealing with the communal shower block. Dinner at the only restaurant is passable, park staff were wonderfully helpful. Well worth the trip.