Firefox OS's Launcher - Image Credit Mozilla
As of Tuesday, Android devices are able to run the Firefox OS 2.5 Developer Preview. Due to the fact that it is installed and used as a third-party homescreen, you don't have to lose all of your data to test it out. You don't even have to have in-depth technical knowledge of Android or software in general.
Although it is easier to install Firefox OS as a launcher, it is possible to do a clean install of Firefox OS onto on Android device. However, doing so is not recommended due to the myriad of problems that could arise. For instance, it would cause your device to only work with Firefox OS and require all of the data on your Android device to be deleted.
The Firefox OS 2.5 Developer Preview contains many features worth trying out, such as Firefox OS’s Pin the Web feature, which allows you to add any website to your homescreen. The added website will then function as if it is a real app. This enhanced experience would be especially useful for websites that you visit frequently, such as social media or news websites.
This version of Firefox OS also includes the Firefox Marketplace, which is Firefox’s app and add-on store. Although the Firefox Marketplace does not have the best collection of apps, it still can be helpful to have another app store in addition to Google Play.
The Firefox OS 2.5 Developer Preview also works with your existing Android apps, so it shouldn't impair your ability to do what you typically do on your phone. But, keep in mind that it is a developer preview, which signifies that there will surely be bugs throughout the software. These could potentially make it difficult for you to use your phone, depending on the severity and quantity of the bugs.
If you're interested in testing out the Firefox OS 2.5 Developer Preview, you can download the APK file from Mozilla's website. Then, simply install Firefox OS and set it as your device's launcher and you're all set to begin using Firefox OS on your Android device.