works decently well for everything I've tried to use it with. That said, I did notice some problems while editing Wikipedia:
*opening the find/replace dialog under certain circumstances (such as when my view is assumed in) causes page elements to move/scroll (seems like it has something to do with highlighting the target text box)
*replacing things doesn't seem to be recorded in the undo/redo history
*although it appears to be only a visual bug (the text that gets changed matches the search term), it doesn't always highlight what it's actually going to change. This may have something to do with the shifting effect mentioned above, but it's hard to verify that in my position as a user. Good luck, developer.
The first when I could live with, but the second one and especially the last one in conjunction with it is, well, a bit hazardous if I can't undo what I didn't know I was going to be replacing. I can't in good conscience give this 4 stars if it risks replacing the wrong thing, even if the highlighting is purely visual and it replaces what actually matched. Sorry.