BTW, if an app fits nicely into the AppEngine ecosystem, that is great. On the other hand, I have not seen any compelling advantages to Google's VPSs, etc. over competitors' offerings. All of them are good.
But minimal price of support, $150/month, makes it expensive enough for side-projects, and I think side-projects is the main force of adoption.
Again from my experience: I created managed VM (on Google Cloud Platform) to test it, with "autoscale" setup. After testing, I tried to remove it, removed successfully, but then I noticed I'm still paying for it - instance was recreated, as I suppose, because of "autoscale". I will not pay $150 to solve $11 issue, so I just turned off billing in that project, but I don't think it's cool to don't have even minimal support from hosting, so I'm not sure my next side-project will be hosted on GCP.
I've also had instances on the Python side where I was using lxml, updated my site, and it stopped working because it couldn't find lxml. I followed their directions[2] and it still wouldn't work. I rolled back my code, still wouldn't work. Without a better log messages than, "Cannot find library", I was "forced" to move to Digital Ocean and run it all myself.
Finally, their Cloud Monitoring[3] falls down all the time. I realize it's beta, but I get an email about once-a-week because of a failure.
I'm a fan of Google in just about every other area, but they're really so far behind Amazon it's sad...
[1] https://cloud.google.com/appengine/docs/java/modules/#Java_I... [2] https://cloud.google.com/appengine/docs/python/tools/librari... [3] https://cloud.google.com/monitoring/