I've been using App Engine for a couple years now for small apps and personal projects. This is my view from using AE for running 10 or so hobby projects.
Pros:
Cons:
sys
module functions are blocked also.Now, that's for App Engine. The newer Compute Engine is a VM you can spin up and do whatever you wish. I don't have any experience using it so I can't add anything to the above pros and cons.