Jorge <1gato0a@gmail.com> writes:

> What is Emacs really good for?  Is it a good personal information
> manager?

> Can you manage your information (todo, grocery list, etc.) and sync
> with a smartphone?

Yes. Org-mode[1] (now part of Emacs) is by far the best PIM that I have
ever encountered. One can think of it as Ecco Pro[2] on steroids.

> If you can't sync with a smartphone, how do you manage the grocery
> list?

One can sync Org-mode with smart phones (Android & IOS) via MobileOrg[3].

> Is it a good calendar?  Can you easily collaborate with colleagues who
> use Google Calendar?

One can sync Org-mode with Google Calendar several ways:

    http://orgmode.org/worg/org-tutorials/org-google-sync.html

or just use MobileOrg, which will take care of that for you.

> Is it a good email reader?  Does it work with gmail?

Yes, via IMAP. 

Charles

Footnotes: 
[1] http://orgmode.org/

[2] https://en.wikipedia.org/wiki/Ecco_Pro 

[3] https://github.com/matburt/mobileorg-android
    http://mobileorg.ncogni.to/

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