Also if you're into crypto you should go to the summerschool in Croatia or the workshops at Eurocrypt!
I think the differences between CCC and DEF CON are roughly:
- CCC is much more political, more about making statements about privacy, etc. There are often journalists there, and there's much more of a balance between political/cultural/privacy issues, and the tech side of hacking.
- CCC is based in the European hacker counter-culture which is quite different to the US hacker counter-culture.
- CCC is a bit more community focused, being very low-budget, accessible ticket prices, more hostels than hotels, etc.
So I might be worth it for people who haven't experienced that sort of thing. But otherwise I would recommend watching online with some friends and travelling someplace else for new experiences.