I've received massive amounts of questions about the same issues on iOS 7, so I'm posting the answers here so I don't need to repeat it.
First: Make sure you have the latest Substrate
Many issues with iOS 7 have been fixed with the release of Cydia Substrate (also known as Mobile Substrate), version 0.9.5000. To update, allow Cydia to refresh, then tap "Update All" on the "Changes" tab.
Tweaks not working on iPhone 5s, iPad Air or iPad mini (2nd generation)?
Unfortunately, there's a very bad situation - for both users and developers - with the latest devices and their 64-bit CPUs. All parts of iOS on these devices have been built for the new CPU, and an increasing number of App Store apps are too.
However, 64-bit apps do not support 32-bit tweaks. This means that every tweak in Cydia must be updated for the new CPU. Currently, a small number of tweaks support it, but more and more should be updated fairly quickly.
If you're a tweak developer, you should check out this dev wiki page about updating tweaks for iOS 7 and arm64.
All of our other tweaks that may or may not work
We will be testing all of our tweaks and writing fixes for features that are broken by iOS 7. This also means that they will be updated to support the iPhone 5s at the same time.
Please be patient as all of these updates happen - not just for HASHBANG's tweaks, but all other tweaks in Cydia. As I mentioned at the start of the post, we're receiving large numbers of emails about tweaks not working, so please keep this in mind. Thanks!