I recently decided to try out Sparrow for Mac OSX while I patiently wait for the new OSX Mail client to be released. I'll admit, at first I was skeptical. The first thing i tried doing was giving it to my wife. She didn't like it because she said “it looked too complicated”. I completely understand that actually. Not having button labels is actually the reason I don't use Reeder for my news client.
- Ability to set colored flags for IMAP mail (similar to the way you can do it with google mail).
- Unified Inbox
Sparrow does have a lot of great features, and it definitely worth checking out.
It's simplistic view for the Inbox and Starred messages make it a pleasure to use. It's really close to becoming a full mail replacement. So close, in fact, that I find myself switching back to it in-between my Postbox sessions. I realize that Sparrow is the new kid on the block, but if it wants to compete with Apple's upcoming mail client, it has to keep moving at a lightning pace.
Overall, I give it a 3.5/5
(note: that I know my requested features are currently in development, and once they are ready for prime time, I will bump my rating to a 5/5).