The ORM is bad because it is a poor abstraction of SQL. This manifests itself in several ways, the largest being little control over the SQL queries generated.
The poor abstraction really causes problems when you need to do anything beyond the simplest of use cases. To achieve even modest performance gains, you're better off hand writing your SQL. Additionally, doing even the most trivial of trivial aggregate queries will also mean that you're hand writing SQL.
SQLAlchemy is light years beyond the django ORM in this regard.
On the CDN urls, you can just change them to use protocol relative urls.
It Looks like the jquerytools cdn doesn't support HTTPS, but you should be okay to use this one from cloudflare
One thing to be aware of when storing sensitive information in environment variables, is that it is possible to view the environment variables a process is using.
Yes RDS is like any MySQL db. The key word there being MySQL. If you want to use another data store like say, postgres or even some NoSQL solution. You're outta luck.
As for platform lock-in, my comments were less towards the web services level and more about system level concerns. It's not entirely clear how you would run persistent background tasks (read: celery). This doesn't even get into the headaches of learning yet another DSL to define OS packaging requirements.
That being said, IMO this would be great for simple apps, with no strenuous requirements. In addition, anything that allows more people to easily deploy their django apps is a good thing.
A couple friends and I just spent the past 48 hours building an app that recreates a lot of this functionality. Some key things to note with this is that you're stuck with RDS, and locked in to amazons platform choice.
Here's a gist I made the other day demonstrating this. https://gist.github.com/jawnb/cd7a899cac5300c01709
The poor abstraction really causes problems when you need to do anything beyond the simplest of use cases. To achieve even modest performance gains, you're better off hand writing your SQL. Additionally, doing even the most trivial of trivial aggregate queries will also mean that you're hand writing SQL.
SQLAlchemy is light years beyond the django ORM in this regard.
Don't take just my word for it though, here's a talk Alex Gaynor gave saying the same things. https://www.youtube.com/watch?v=GxL9MnWlCwo