I already have to remember my OSX Password and iCloud Password. If I enable two step authorization I also have to remember iCloud recovery key. But that’s not all, in the case of using two step authorization, Apple also requests me to create app specific passwords for any third party apps that access iCloud. The last part is a deal-killer for me. That’s just too many passwords.
If you do however choose enable two step authorization, make sure not to forget the recovery key.