I've just installed OS X Mountain Lion... and gone back to Apple's Mail (no more Sparrow). I'm too tired of chasing another email/to-do client that might get acq-hired, with no future support.
Having said that, the idea behind .mail app is elegant, well thought and a step forward. Kudos.
"Launching" on the heels of the announcement from Sparrow seems like a poor choice. A lot of people felt like they just got dumped. Then again, this is just another fancy "Give us your email address for whenever we get our act together" page, so maybe people will be more lenient.
Having said that, the idea behind .mail app is elegant, well thought and a step forward. Kudos.