The new version of the app specifically adds off-line mode (I'm in the Test-flight group), which is nice atm, it just works, even though I can't access the webapp (ok now, 10 min later, I can).
The new version has been solid! Only issue I have is with the swiping gestures not being 100% yet (they don't discriminate between swiping in from left [back to overview] and swiping left [next/prev mail]).
