Exchange's IMAP and SMTP implementations work fine. The only really awkward things I've seen are that IMAP search doesn't quite work and calendar invites don't do the magical thing you want. But it's definitely reasonable to use a text client for most things and pull up OWA for the occasional edge case.
Honestly, it's Gmail I've had more trouble with, because labels aren't really folders as the IMAP spec envisioned.
Honestly, it's Gmail I've had more trouble with, because labels aren't really folders as the IMAP spec envisioned.