Before they'd be affected by Route 53 outages, Cloudfront outages, and S3 outages. Now they can add Lambda outages to that list too.
It's also unclear how this actually solves the problem. Now if S3 in _either_ region is unavailable they'll start to fail 50% of uncached requests. I'm guessing they're using Route 53 health checks with some cloudwatch alarm to cut over to one region when they think the other is unhealthy. Presumably this is covered in the unavailable part 2.
I'm mildly skeptical that this is worth the increased risks plus the increased cost from running Lambda@Edge on cache misses.
It's also unclear how this actually solves the problem. Now if S3 in _either_ region is unavailable they'll start to fail 50% of uncached requests. I'm guessing they're using Route 53 health checks with some cloudwatch alarm to cut over to one region when they think the other is unhealthy. Presumably this is covered in the unavailable part 2.
I'm mildly skeptical that this is worth the increased risks plus the increased cost from running Lambda@Edge on cache misses.