Although I've been a developer for years I've never used a PHP IDE - I've always just used a decent editor. What am I missing? I generally code on local servers so I can debug as if my code were running on my own machine, I have code highlighting, I have shortcuts set up to look up function names and so on. Is it worth investing the time in learning to use a full IDE? Is it worth investing the money in purchasing one?
Looking at (the slightly aging) http://stackoverflow.com/questions/116292/what-is-the-best-ide-for-php I would probably go for PhpDesigner or possibly Eclipse.