imessage is great, loads of my friends have iphones, ipads etc... and it integrates seemlessley into the messages.app.. saved my self loads already in this respect not sure why you would want to turn it off, as if the recipient doesnt have an iphone with iOS 5.0 it will just automatically send as an SMS... if it fails to deliver the imessage, it auto re-sends as an SMS too. yep, ive configured my push notification sounds, incoming / outcomign email tones etc....