This is the original version of SF Launcher. For the best experience on Android 4.1+, switch to SF Launcher 2 (https://play.google.com/store/apps/details?id=com.jackthakar.sflauncher), a complete rewrite of the original SF Launcher. If you're running Android 4.0 or you prefer the old version, you can still download it here.
The plus key for this app (https://play.google.com/store/apps/details?id=net.alamoapps.launcher.plus) is now free for everyone. It currently adds support for icon packs, hidden apps in the list, and font options in the header and app labels. There is also a link to it available on the settings panel for easy access. Not all icon themes will work, but most ADW-compatible themes should.