Purchased this app when I had an iPad gen 1, and thought I had wasted my money. Performance was poor, connections to my companys exchange servers through OWA was dodgy and crashes were frequent. Needless to say this is a unless app on an iPad 1.
Have an iPad Air now and this app rocks! All of the issues I had on the gen 1 are history. Performance is snappy, on par with the iPad mail app - only now I have calendars, email and tasks all in one place.
If you have an iPad Air and can access your exchange account through OWA - 5 star app, otherwise cant recommend.