I use it daily. It's a lovely email client. Close to the Unix ideal of doing one thing, and doing it well. Integration with other utilities (notmuch, isync) for indexing and sync'ing is very easy, thanks to close adherence to Unix principles, and gets you a very neat setup. Nothing to envy from Gmail.
> Close to the Unix ideal of doing one thing, and doing it well. In my opinion this concept does not work for most non-cli programs. How do you actually define this "one thing"? Is "reading an email" one thing? And "writing an email" another thing? What about "spellchecking the email"? What about "managing all my email contacts"? What about "back up my emails"? What about "sign email with GPG"? Do all of these things…
It seems that the unix principle is most relevant when compiling a C program takes too long and no interpreters exist that are fast enough. So, you figure out all the higher level functionality that you will need for system administration and compile that long before needing to do any sysadmin work. When a problem arises on a system, you can write a shell script that uses those already compiled commands, instead of writing a C program and waiting for it to compile. If your initial code sucks, you don't have to debug and recompile; you just debug and re-run the script.
Compiling C programs is now substantially less time consuming, so you could use C for sysadmin work (shudder). C shell was perhaps a similar attempt to get the benefits of C, but without the downside of compilation times. I seem to recall some essay on the harmfulness of using csh, so C will continue to keep its place.