Google CDN looks very similar to what Cloudflare Free Plan offers. A no-Frills, fully automated setup with little or no control on how your content is being delivered. Main difference with Cloudflare being that Google forces you to use GCP as Origin and you have to pay for the CDN service (Bandwidth, purge, requests...) which Cloudflare offers for free and you can use any Origin server.
Not sure why someone would use Google CDN when you can get the same for free with Cloudflare. Moreover, Cloudflare provides Security up to L7 with WAF whereas Google Cloud has no Security features. Anybody know how DDoS (L3/4) mitigation works on Google CDN?
Now if you want control and the ability to set up your own policies (Cache Control Headers, redirect, complex cache key manipulation, etc...), Google Cloud is not going to be what you need, at least for the time being and you would be better of with EdgeCast or Akamai. Faslty is an interesting option too but their network is very small compare to EdgeCast or Akamai. Fastly is about 1Tbps of capacity whereas Akamai or EdgeCast are > 20Tbps.