It's a small shop, but from my few experiences, I greatly appreciated it. We were in Iceland during the holidays, and very few stores were open. I went to this shop several times and the guy who helped me was very friendly. On one occasion he offered my children sweets. On a second occasion he gave me a free beer since I took him up on a recommendation. He seemed sincerely interested in offering good service to his customers, even though I was clearly a tourist (and many locals can get frustrated with tourists). The shop was close to my Airbnb which made it really convenient. I think it's really important to support small, local businesses like this one!
Good store
They charge 100 ISK for using bathroom !