Here's my complaint:
I, and many others, spent a lot of time figuring out how to write apps that do it the "app engine way":
* Fast completes (30 second timeout)
* Offloading to task queues when you cant
* Channels
* Blobstore two-phase upload urls
* Mail eccentricities
We did so, because we believe Google when they told us
If you write your apps in this really weird way then we will be able to give you scale and cost benefits that you wont be able to get elsewhereWe believed them, because it seemed reasonable. We laughed at those who complained that django would hit the 30-second limit: "Its not a general hosting! Figure out the App Engine way!" And we educated on how to do it right, and many were happy.
Well, it turns out that it is general purpose hosting, with all of the costs, and yet also with all of the (once rational, now bullshit) idiosyncrasies.
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But that's not the biggest complaint. The biggest complaint is that when my friends and peers objected to App Engine, its strange requirements and its potential lock in, they were right and I am a fucking naive idiot. And I really don't like to be proven a naive idiot. I put my faith in Google's engineers and they have utterly destroyed my credibility. THIS more than anything is the cost to me.