Having now worked with the new installer, there is nothing wrong with it, and provides sufficient scritpability, if that is a word.  I only have two (and a half) thoughts on it:

1. This should be more prominently documented.  The addition of the new web installer is listed in What's New, but not that the change to the new installer, and lack of the old msi installer.  This is noteworthy for anyone who does scripted installs of python.

2. passing /? should list the available kay-value arguments.

2.5. The help should really be to stdout... If you are running /? on an installer executable, you are in the command prompt - no one creates a shortcut to an installer exe then modifies that shortcut to add the /? argument.