Spent a summer and a winter in Keflavik. Gotta day summer was much better, though the northern lights were spectacular.
Fell victim to the color coding reverse on the gas pumps (green is gasoline and black is diesel). Fortunately caught my mistake after only having put around 4 liters of gas in my rental diesel, and never noticed any I'll effects.
As with the oil, nothing in Iceland is cheap...except for electricity.