I've never seriously used anything except a real client for e-mail (ZIMACS, then Thunderbird, then Apple Mail, now mutt), and any time I have used a web-app for e-mail, the whole process is just frustrating. I'm especially surprised when I come across people who say they ``live in their Gmail'' and actually do live in the web-app.
The worse thing is totally different interfaces between different mail providers. It makes impossible to have multiple email addresses and manage them in a sane manner.
Do you have any primers to use mutt? I really wanted a terminal-based alternative to Thunderbird in case I need to ssh from somewhere, or if I'm in a hurry, but the man page alone scares me.
Just start it? In the standard config, it has a help line that tells you about all the most common key bindings, I'd think it really isn't difficult to get started and look things up in the manual as needed. If you are not on a fully configured unix system with an MTA and local mail spool, the only thing you'll have to set up to get started should be the mail server config.