Personally I'm real suspicious from the time I was on a project using AppEngine, we got sandwiched between Google deciding "1 year" was an appropriate time to declare AppEngine v1 deprecated, but AppEngine v2 was still in "beta" and was removing a bunch of APIs we depended on, while basically saying "oh yeah, setup something completely different if you want something like this" (appengine datastore or whatever vs. "it's gone, um, redis maybe?")

So we were stuck with a product which we were writing against something that the official word was would no longer be supported by the time we launched, while being told to develop against the platform which is "beta" and they don't want to commit to supporting the feature set of - and which plain couldn't be used yet at the time they told us this.

This is just a ridiculous way to run a commercial platform offering (aka: why I always tell people to use boring VMs for as long as possible).