Better search and better organization of the document (TOC, index search, etc.). And reading/searching Info manuals is a lot more convenient in Emacs Info-mode.
The man page for gcc goes on and on. Try it.
The info for gcc is a printed book, which is also accessible in the shell as hypertext (which predates html).
Huh? grep is not part of coreutils.
I know this is late but you are right. For some reason I thought info was only fore coreutils, but it seems I was wrong. I only ever used it for coreutils, but hey, thats good news to me!