Install It If You're Having General Performance Issues
If you're already on iOS 9.3, iOS 9.3.1 or iOS 9.3.2, and you're dealing with performance issues or bugs, the iOS 9.3.3 beta might be worth your time.
We don't have a full change log but Apple says that the iOS 9.3.3 update will include bug fixes for iOS 9 problems and under-the-hood performance improvements. In other words, it could improve your device's performance.
What's nice is that you can trial the iOS 9.3.3 beta and then drop back down to iOS 9.3.2 (or iOS 9.3.1, for the moment at least) if you decide you don't like its performance.
If you want to see how iOS 9.3.3 might change your device's performance, you might want to think about giving the beta a try.