I'm having trouble syncing my outlook calendar, actually. Now, some appointments aren't synced although they are in the same calendar. Also, updates to those appointments that do sync aren't updated. Seems like Cal doesn't check for updates once the appointment is downloaded. Other than that, great app!
One more thing: Why not make the week view appear when going into horizontal screen orientation and have the appointments appear in a schedule (like the stock calendar app) rather than an agenda view for the entire week?
//edit: after readding my outlook account I got all my appointments synced but an hour (and / or app restart) later, those missing before are missing again.