The Lockscreen app merely allows you to easily create backgrounds for the locked screen (that you set up in the iPad's settings). It's just an easy way to modify a photo to show what info you want to display when your iPad is locked.
Once you've created the screen, you save it to the iPad photo library. Then you go into your iPad's settings and change the lock screen background to be the one you just made. Unless they know your passcode, no one should be able to access your iPad ... but they will see the info you've entered.
And, AFAIK, it makes no difference if you keep the lockscreen app or not - once you've made a new picture. The password setting and background are all done through the settings, not the app.
There is another app which I've got that let's you put in "In Case of Emercency (ICE)" info (iEmergency+), but I'm with someone up thread ... still not comfortable putting personal info out there for all to see. Let them work for it as they try to break my passcode...
Mariilyn