I now understand. I have been using the (surprisingly stable) iOS 5 beta and beta 2 for the past two weeks or so, and of all the new features–notifications, widgets, photostream, geo-fenced reminders, etc,–iMessage is what impresses me the most.
1. It’s one app
In all of iOS 5, there is nary a mention of “iMessage”, save for one instance buried in the Settings>Messages>iMessage ON/OFF. You get your SMS and MMS messages in the Messages app, as you did before. Now you also get iMessages (both text and multimedia) in the same app, even over 3G or EDGE. You get notified the same way. You can’t distinguish between SMS and iMessages except for…
2.There are only very subtle ways you can tell iMessages from SMS
SInce it is all in one app, one of two ways you discern between iMessage and SMS is that the former’s “cartoon talk bubbles” are blue instead of the green of the latter. The other way to tell the two apart is even more subtle–the field where you enter text has “iMessage” in faint grey text (conversely, it says “Text Message” when you are about to enter what will be an SMS).
3. It checks every time to see if it can send an iMessage over an SMS
The way that the Messages app knows whether the person you are trying to contact should be sent a free iMessage rather than a costly SMS, is that it checks every contact as soon as you select it. Meaning, you go to someone’s contact info, select “Text Message” and it opens the Messages app with the default set to Text Message. Then you see a little spinning wheel next to their name in the To: field–this is your iPhone scanning to see if your contact has registered for iMessage. It does this every time you start a new conversation, just in case your friend got his or her act together and got on the iOS bandwagon since your last message.
4. iMessage conversations show up on your iPad
Conversations you start on your iPhone show up on your iPad, and vice versa. Also, new iMessage notifications that are sent to your iPad disappear if you have read them on your iPhone first (although the syncing between the two devices works inconsistently–probably a beta bug).
5. Just use it
Really. Just use it. I originally got all this information from watching the WWDC keynote, but it’s the difference between “knowing” and “understanding” now. I now understand why BlackBerry users love their BBM. I now understand why iMessages will soon be everyone’s favorite new feature when iOS is released.