Amazon just added 2 new metrics within sponsored products RoAS and Conversion Rate. you can view them in the new search terms view within individual ad groups.
RoAS is the most accepted metric for measuring the efficiency of ad spend, however, for sponsored products amazon has always used ACOS as the main efficiency metric.
The same is true for conversion rate, which is one of the most important advertising metrics, yet has never been part of sponsored products interface reporting (Both have been available in the downloadable reports for some time)
Interestingly, these 2 new metrics are not available anywhere else in the campaign manager, but hopefully, we get to see them added across the platform soon.
Have you noticed these new metrics?