One thing that is absolutely horrible about iOS 6 is that the Mail app is no longer as reliable as it used to be. It's a highly primitive mail app (I wish there was an alternative, but Sparrow is even worse), but at least it used to have that one quality until iOS 5: it was super-
reliable.
Ever since I upgraded to iOS 6.1, it periodically happens to me that emails (usually those with attachments) remain stuck in the Mail app's Outbox, refusing to get sent. Lots of users are
complaining about this. Nothing helps under such circumstances: force-quiting the Mail app, or even resetting the whole iPad. The message(s) just remain stuck in the Outbox, making the sending of emails impossible. You then need to start fiddling around with switching Airplane Mode on/off, switching cellular data on/off, hoping and praying this will resolve the issue. You typically also need to manually delete the email you wished to send, with no hope of recovering it later on.
What's even worse, the Mail app now fakes and cheats the user about the email having actually been sent. Up until iOS 5, the "swooshing" sound only was heard when the email
actually left the Outbox. That was very nice: you knew the message was sent successfully. In iOS 6, the "swooshing" sound is heard immediately, as soon as you press the "Send" button -- but it's just cheating; the message may well still be in the Outbox, struggling to get out. Which means I can now no longer rely on the "swooshing" sound as confirmation, but need to check manually every time if the email actually got sent off.
Apple gets a huge
from me for the way the Mail app is no longer reliable in iOS 6. So now it's not only primitive and feature-poor, but unreliable to boot.