Took a test run using gcr.io/cloudrun/hello-image with 128Mb memory and 80 concurrency: cold response about 450ms, warm 2-5ms (as reported by logging). Scaling seems to work, got about 200 requests/s with quick ab-testing. Domain name mapping + HTTPS is nice addition.
Price-point: using 128Mb+100ms "defaults" from other serverless pushes price over $3/million requests. If any concurrent requests going, price/request goes under $1/million. And don't forget network prices, hello-image return a bit over 4kB so that means $0.46/million requests.
Biggest concern is overall latency, from EU I got 1020-1300ms total latencies. Tracerouting address gives 60ms "ping" latency. And sometimes total latency is 220-250ms (less than 10% requests). This really needs some inspecting. Otherwise pretty nice service, I have been waiting something like this :)