Powerline/Airline is one big one -- the status line in Vim is just a character-mode thing, but with a few extra glyphs (for line number, git branch, and arrows/

Powerline/Airline is one big one -- the status line in Vim is just a character-mode thing, but with a few extra glyphs (for line number, git branch, and arrows/wedges, most notably) it looks a lot better than if it's using a more limited character set. vim-devicons is the other big one that this is supporting, which gives you filetype icons. Are these things huge big deals? No. Are they nice things that make Vim's UI look a little cleaner and more informative within the confines of a pure character-mode application? Yes.