The main upsides are:

 - Files are now all in a consistent, standardized format.
 - Dependencies in debian/control are now formatted in way that's friendly with
   `git diff', `git blame' and `git log -p' (one line per package).

The main downside is that we lose the ability to track older changes with `git
blame'.

I think the upsides will quickly outweigh the downsides once we're past
the initial inconvenience.