So you don't like the launcher that shipped on your phone? There are alternatives, and far and away the most popular one is Nova. The big v4.3 update has been in beta for a while, and now it's out for real with a number of important changes.
Here's the changelog for v4.3.
- Night Mode
- Android N Folder Preview style
- Improved search bar configuration
- Bug fixes
The night mode feature will make some people very happy as they can finally avoid the retina-searing effects of white space. Night mode can theme the settings, app drawer, folders, and search bar if you like. That's all configurable in the settings. You can also have night mode flip on when it's actually night and shut off in the morning. Those Android N folders are included in this version as well.
You can get all the basic features with the free version of Nova. Advanced stuff requires the Prime add-on for $5.