Review: LG DoublePlay for T-Mobile
The big appeal of the DoublePlay's secondary display are realized in the messaging department. It offers access to the text messaging app, group texting, email, and social networking functions of the phone. The bottom line is that you can check/send messages from the small display without disturbing what you're doing on the main display (such as watching a movie).
The text messaging application behaves more or less like the full version, but there are some restrictions: You can't add media to messages in the SMS tool. If you want to insert anything other than emoticons, you have to send the draft message to the main display. You can, however, quickly fire off text messages and scan through any received messages and conversation threads. The same set of limitations apply to the Group Messaging feature in the small display. It works fine for scanning through messages and replying, but you can't add media (more on this later).
I was really disappointed by the email functionality in the small display. It only works with the generic email program, and not with the native Gmail application. While it's true that you can set up the generic email app to receive your Gmail, the lack of support for the full Gmail app is mind-boggling and completely negates the usefulness of the shortcut if you use Gmail, as so many people do. Still, it can technically be used to clear out your inbox as well as respond to messages, (or you might not mind at all if you don’t use Gmail.)
As far as the social features of the second display are concerned, it works only with the catch-all Social+ application. That means you can use the DoublePlay's smaller display to read the status updates of your Facebook and Twitter friends, as well as set your own status updates; but that's it.
On the main display, the DoublePlay includes the stock Gmail app, stock SMS app, GTalk, CMAS emergency notification app, as well as the full versions of Facebook and Twitter.