That's a pretty broad question. Rather than talk of switching from asp.net to Django, it's important to just run out and do a few quick and dirty projects to get your feet wet. From there you can make a personal decision about it.

If you're looking to learn new things, instead of just picking up a new framework, I think there is a lot to be said for stringing together your own framework. In that regard, PHP is a really easy way to get started, although the language isn't overwhelmingly gorgeous.

Django does open up some interesting work opportunities, especially it's somewhat over-represented in the small/medium newspaper world.