Just checked gcloud myself, compared to appcfg, I really really like the examples, as in the past, the GUI approach was spammy and insufficient, I like the new CLI based approach, and the documentations seem adequate too (Feedback: You seriously need to send emails when changes happen, new things are added, I'm ashamed that I didn't discover the gcloud CLI and the new documentations up to this point)
For some projects, I'm locked with old versions of appcfg, yet, for deployments and new projects, gcloud seems nice
I think the confusion arises from this: """ Does the method you deploy with, determine the version of appengine your app runs with?! """ - Because, as an outsider, the assumption is that, unless you explicitly set something, the apps should always run with the latest version