Just after the 1.4 update, I was having serious issues with mail. I removed my accounts and re-added them, and things have gotten better.

One thing I've noticed is that even in areas with poor coverage (which is about everywhere for me where I work and at home!), push email is working much better than before. My home mail server is also not getting constant connect/disconnect from the phone. It seems they are now properly keeping the IMAP connection alive for Idle to be able to do its thing. This makes me happy :-)

This was one of the things that was noted to be addressed, and it does seem like things have gotten much better and more reliable on intermittent connections.

Now if only we could get alerts on folders other than 'Inbox', I could get rid of my phone-only account and manage everything in one place as RFC3501 intended.

Just thought I'd throw that out there.