Well, that's like going and buying a new car and saying, my XM radio station presets weren't in the new car so I returned the new car and got my old car back (the one without xm radio.) Why did you not post here before downgrading for some help on how to fix a minor problem? *shrugs*
OS 5.0 handles notifications and ringtones differently so you have to go in and set them up again. Some of it will transfer over but there is a lot of new added features that the old OS didn't have.
Can you be more specific than my backup "wouldn't load?"