I have been using widget locker for a while now, here are some of my favorite things I like about WidgetLocker:
1. Ability to set Custom Wallpaper different from the one used on LauncherPro Plus or other Launchers
2. Ability to remove all sliders! (I hate sliders)
3. Ability to make sure all other buttons don't unlock it (especially the Volume button)
4. ability to use Track Ball to unlock (set back button to 5 second delay to not accidently unlock via this method)
5. Ability to set the following 3 widgets on the Lock Screen:
a. Launch-X Pro Widget (shortcuts: direct dial to wife mobile & work, direct message to wife; shortcut to default camera, Google Talk and handyCalc)
b. Clock Droid Pro
c. BatStat Battery Widget
(Also I tested the Pandora widget on WidgetLocker and it works great)