[nickbauman]

I've found Heroku to be about 10x the cost of AppEngine for the same kinds of apps and users. I don't even want to imagine what it would cost to create my own ec2 sprawl to do what AppEngine can do out of the box. As far as languages go, I've gone to production with AppEngine apps written in Python and Clojure. I've diddled with Go. Unless what you want is something like Node.js, which has its own limitations, I don't see this as a big problem. As far as Datastore is concerned, you can substitute the implementation of it using technologies like AppScale: Cassandra, Hypertable, etc. But I've never seen another structured storage solution in a fabric form that works as well as Datastore for 90% of my problems AT SCALE. YMMV.

[nickstinemates]

FWIW, Amazon has something similar in Elastic Beanstalk. Haven't used either personally, but they are comparable services.

[nickbauman]

EB is more like Heroku than it is like AppEngine. As far as I'm concerned, the thing that makes AppEngine amazing is Datastore and how easy it is to do monstrous, sophisticated Map/Reduce over your data. I haven't even started using Spanner/Dataflow yet. It's an amazing platform (that is not without its rough edges, mind you).