I have an issue where at least half the time I need to force-close the app, otherwise it hangs trying to load new mail. Happened on my iPhone 5 and happens on my newer 6.

I also have this issue. Also, on three separate occasions one of my accounts has just disappeared and I've needed to re-add it.

Almost without fail, switching between my personal and work email accounts causes the app to hang and I have to force-quit it. A fix for that would be nice.

Key feature missing in Apple Mail is sorting by "Important and Unread". I get so many emails, any app without this is unusable. I use the GMail app.