I used the email app to connect to my OWA for work once BOS-IAH. I thought it was fine. It let me continue my normal email and IM communication with colleagues through the end of the business day. I didn't want to pay to read any big attachments, but that's the kind of stuff that I didn't need to respond to immediately anyway.

I found it helpful and worth the $10 for email. The $6 for IM is almost always worth it during business hours.

I don't use it that much because I usuall don't travel during normal business hours.