Yup - we loved it. My top tips would be to plan to cook as much food in your apartment as you can, as there are only a couple of restaurants worth going to, and they’re overpriced for what they are.
Airwaves is a bit like SXSW in that lots of acts play several times throughout the festival, often during the day at free gigs in bars, youth hostels, shops and cafes. The KEX hostel is consistently great and is a really good spot for seeing ace bands at close quarters eg
Plan for at least two full days of excursions (one to the Jokulsarlon glacial lagoon, one around the golden circle) on top of the festival as well, but other sightseeing in the city can be done around the gigs and shows.
Some other tips here: