New Iberia Plus user here, got my avios today and already booked a transatlantic flight with Iberia. Redeeming together with a friend is not so easy because the availability on a specific flight may not be enough for two people, and one of you may get an error on the payment page. You first have to search for 2 people, look for suitable dates, and then book individually. There is still plenty of availability in spring 2019, but that will fill up quickly since many Iberia flights only have 1 seat available.