... probably never had to engrave complex music in a professional way.
I concede that LilyPond isn't easy to use for the 'first time user', but after a reasonable time of using it, you will be faster than with any other application with a graphical user interface.
And the sheet music produced with LilyPond looks really professional and there is very less you can't do with LilyPond.

I also tried an X-Windows based graphical interface to LilyPond (which produces the LilyPond source code) but I returned to pure LilyPond immediately.

For me, LilyPond is the best music engraving software.


p.s.: I've seen one comment who recommended Finale Notepad instead of LilyPond *LOL* Did you really ever tried to edit a music sheet with many staves and lots of lyrics stanzas?