We've eaten in some very expensive restaurants, incl. a few Michelin stars, and the the Lava really surprised us. We were expecting reasonably good for and a stiff bill, and we got very good food and a stiff bill (18,600 ISK = about £98 for two incl. 10% tip)
But the main thing was the food was actually remarkably good. We ordered the Icelandic Gourmet menu - three courses for one of us and two courses for the other, plus some glasses of wine and some fizzy water. We'd ordered this menu to try some new things, and they were very well presented, extremely well structured and prepared, and sublime in taste. No regrets at all.