Sony releases Xperia Assist app in the Google Play Store2
Obviously, the application is not meant to be downloaded by owners of other smartphone brands, so if you don't own a compatible Xperia handset you won't be able to install it. On the bright side, it will make it easier for Sony to update Xperia Assist without having to push another firmware to its Xperia phones.
The Xperia Assist application is supposed to learn how you use your Xperia smartphone and adapts to give you the best experience. Also, it offers contextual tips based on the usage patterns and device surroundings.
It's the main go-to app if you're a newcomer to the Xperia brand and the only app that offers consistent help in making the best out of your Xperia smartphone.
Keep in mind that since the app uses analytics software to collect and aggregate statistics, you'll help improve the app by simply using it.