From what I've experienced so far it works pretty well... when i hold the mouse over the pattern it displays information about that part and so on.. Thanks for making me look up this plugin. I have little to no knowledge about regex, so this will be really usefull for me!
also what i like is the direct access to the function list inside Eclipse.. you can highlight a function in your document and press Shift+F2 and it'll open the online manual page for that function.. as well as a full listview of all functions
like several people here including me has said already... Eclipse PDT is a great editor
