You can also have emacs run as a daemon(1).
That way you never have to wait.
Being able to remotely open my editor (either from a terminal, or with X11 forwarding) with all the files I have open, exactly where I left off is incredibly useful.
A few years ago, I started using one daemon per project with server-use-tcp, each with a slightly different theme so I can easily tell them apart.
(posted from emacs-w3m)
Other big benefit is starting emacsclient is basically instant, so opening a file from a webbrowser or whatever is super fast (some folks have 30 second or longer emacs startup times).
Only real downside is it really sucks bringing back your state when emacs crashes and you have hundreds of buffers open for multiple projects across 20-30 emacs clients.