Ok, I'm surprised the ranking is so low. I was there as part of a tour - it felt a bit like a university dorm in the sense there are so many rooms and so many tour/schoolgroups. It didn't bother me too much though. The food in the cafeteria for breakfast wasn't bad considering I expected worse - range was pretty good, staff were reasonably helpful. Room was ok space - slightly tight for my large suitcase though! Bathroom ok size. Not sure the windows in the room were airtight - I could hear the Icelandic winds outside but it was very cold & windy when we were there....Nothing special in terms of design - but for this price bracket, you can't expect much. It's a basic hotel.
I probably wouldn't' stay here on my own as its location is not that close to the centre of the action in the city - I stayed at the Alda Hotel which is a lot more expensive but has a great location that makes it easy to get around. I think Hotel Cabin is a good 30 min walk from the good stuff in town so keep that in mind.