MARUKO DRINKING TEAM Look, sure, you don't need this app if you are a Mac developer. But if you are, you don't want to use a text editor. That might be fine if you only need to make a couple of edits. And Apple's plist tool is only very slightly better.
If you are frequently revising plist files used in complex apps, they often contain long lists of default preferences, configuration info, etc., and PlistEdit Pro will save you a lot of time: smart row-based cut and paste, drag and drop, undo, the ability to duplicate large dictionaries and arrays (or any property list data), and intelligent search features that understand keys and values and let you restrict searching to either or both. If you do much Mac development, the time savings and convenience easily justify the inexpensive price.
(Version 1.2.1)