BA is still tweaking this relatively new product.
When it was rumoured, I assumed it would cover the entire cost of a flight if you wanted. People were disappointed by the low value per Avios combined with the low cap on what could be used. (Low value per Avios and no cap would have been ok in my view.)
Since then BA has been experimenting with both the value per point and the cap. They can't seem to get happy with an equilibrium that works.
PS. A Pret server, who I thought wanted to evict me after sitting here for an hour after spending £4, actually wanted to give me a free coffee and even brought it over to my table for me! This is not even my usual branch.