after years of experiences in google appengine, i switch to other cloud services now.
i think google appengine is actually an old fashion service in cloud computing industry. which is slow to new technology, difficult to deploy, time wasting to learn the apis and lacking of a lot of features you need in languages you use.
regardless of google's large community, i would not suggest anyone to use google appengine.
[newer paas]
i strongly recommend you to use openshift, appfog, heroku .etc's new paas cloud computing technologies, which are far more extensible, less change needing, more migrable from one platform to another, more freely coding in the beauty of the natural lanuage and its standard libraries without ugly platform specific apis.
[iaas]
if you want more control over the running os environment, you may give linode, digital ocean, amazon, google cloud engine, microsoft azure etc. iaas providers a try.