I'm in the middle of this process, but from an even older version.

Since 1.7 introduced migrations, I recommend upgrading to 1.6 first and getting your South migrations caught up with third party apps. Some may have data and schema migrations e.g. django-photologue. Then jump to 1.7 or 1.8.

You'll likely have to update your requirements.txt with the latest packages, so you'll want to see if they're compatible with the version you're upgrading to.

I recommend keeping it up-to-date with every release if possible. Much easier to make incremental updates than spend months on upgrading 4 major versions.

And read ALL the release notes.