Why does it scare you? It's good to be wary of the upgrade process.. but this is why you have (I hope!) database backups and source control (as a minimum). Then at least you can roll back. Then it's just extras after that, test coverage, staging servers etc. etc.

Anyway, upgrading is a fact of life once you're using a framework (unless you want to get hacked) so best to get used to it :)

Good luck!